An electrical engineer in Germantown, Tennessee, has been searching for big prime numbers for the last 14 years, as a volunteer who uses his computer to run a software designed to do exactly that. In late December, Jonathan Pace, 51, struck gold when his machine pumped out the largest known prime number yet.

What is this number? Well, since it clocks in at a humongous 23 million digits long, writing it down in its entirety, five digits to an inch, would require over 73 miles of space. And at the speed of five digits written every second, writing the number out would take 54 days, without any breaks. So no, that number itself won’t be written out in full here.

However, it is the result you get if you multiply the number 2 by itself 77,232,917 times, and then subtract 1 from it. So that you don’t have to go through the process of verifying it for yourself, an online collaboration called Great Internet Mersenne Prime Search (GIMPS) — whose software Pace was running — already did that.

The number was discovered Dec. 26, but GIMPS made the announcement Wednesday, having spent the intervening time running “four different programs on four different hardware configurations” to confirm proof of primality.

The newly discovered number has exactly 23,249,425 digits and is called M77232917, since it also belongs to a rare class of prime numbers called Mersenne primes. These numbers are always 1 short of a multiplication of 2s. For instance, the first Mersenne prime is 3 (2x2-1), the next is 7 (2x2x2-1), after that is 31 (2x2x2x2x2-1) and so on.

The new addition to the Mersenne primes is the 50th number of its kind to have been found, and it beat the previous largest known prime number, also a Mersenne prime, by 910,807 digits. That number was also found by the GIMPS collaboration, in January 2016. In terms of writing it down, the 49th Mersenne prime would be about 3 miles shorter than its successor.

Mersenne primes are named in honor of Marin Mersenne, a French friar who studied them almost four centuries ago.

For his efforts, Pace won a $3,000 GIMPS research discovery award. If you would like to have a chance of winning another such award in the future, you can volunteer with GIMPS by installing its free software on your computer and running it in the hope of finding the next Mersenne prime. The program can be downloaded using this link.

GIMPS hopes to win the $150,000 award, announced by the Electronic Frontier Foundation, for discovering the first prime number with over 100 million digits. There is also a $250,000 award for finding the first billion-digit prime number.

Really big prime numbers don’t have many practical uses yet, but cryptography algorithms based on prime numbers have been developed. </s> Maths fans can’t get enough of numbers that are millions of digits long and can only be divided by themselves and one. Now, through a collaborative effort, utilising computers distributed around the world, they’ve discovered that the number 277,232,917 – 1 is prime.

The discovery was initially made on 26th December by a computer volunteered by Jonathan Pace, as part of the Great Internet Mersenne Prime Search (GIMPS). Pace, a 51-year old electrical engineer based in Germantown, Tennessee, has been hunting primes for over fourteen years and his belated Christmas present is eligible for a $3,000 reward from GIMPS.

The new prime number, known as M77232917, is one million digits larger than the previous record. It is also a particularly rare type of prime called a Mersenne prime, meaning that it is </s> At more than 23m digits long, the number is something of a beast. But for mathematicians, the latest discovery from a global gang of enthusiasts is a thing of beauty: the largest prime number ever found.



Known simply as M77232917, the figure is arrived at by calculating two to the power of 77,232,917 and subtracting one, leaving a gargantuan string of 23,249,425 digits. The result is nearly one million digits longer than the previous record holder discovered in January 2016.



The number belongs to a rare group of so-called Mersenne prime numbers, named after the 17th century French monk Marin Mersenne. Like any prime number, a Mersenne prime is divisible only by itself and one, but is derived by multiplying twos together over and over before taking away one. The previous record-holding number was the 49th Mersenne prime ever found, making the new one the 50th.



“I’m very surprised it was found this quickly; we expected it to take longer,” said Chris Caldwell, a professor of mathematics who runs a website on the largest prime numbers at the University of Tennessee at Martin. “It’s like finding dead cats on the road. You don’t expect to find two so close to one another.”



The new prime number was originally found on Boxing Day by the Great Internet Mersenne Prime Search (Gimps) collaboration which harnesses the number-crunching power of volunteers’ computers all over the world. In the days after, four more computers sporting different hardware and software were set the task of verifying the discovery. Those computers confirmed the result, taking between 34 and 82 hours each.

To find M77232917 in the first place took six full days of nonstop computing on a PC owned by Jonathan Pace, a 51-year old electrical engineer from Germantown, Tennessee. It is the first prime that Pace’s computer has churned out in 14 years on the Gimps project. He is now eligible for a $3,000 award.

When asked about mathematicians’ fascination with such mammoth numbers, Caldwell said: “They are exciting to those of us who are interested in them. It’s like asking why do you climb a mountain.” He compares prime numbers to diamonds, with small ones finding uses in encryption and other applications, but large ones being more like showpieces. “That’s what we’re talking about here: it’s a museum piece as opposed to something that industry would use,” he said.

Curtis Cooper, a professor of mathematics at the University of Central Missouri, found the previous record-holding Mersenne prime in 2016, the fourth prime he has helped to find through the Gimps project in 20 years. He said he was a little sad at having lost the record so soon, but added: “I’m really happy for the whole organisation and the guy who found it. He’d been searching for 14 years, so he’s worked as hard as I have.”

“Discovering new primes, which are things you can touch, it’s the realisation of my love for mathematics. That’s the appeal for me,” he said. </s> The World Has A New Largest-Known Prime Number

There's a new behemoth in the ongoing search for ever-larger prime numbers — and it's nearly 25 million digits long.

A prime is a number that can be divided only by two whole numbers: itself and 1. The newly discovered number is what's known as a Mersenne prime, named for a French monk named Marin Mersenne who studied primes some 350 years ago.

Mersenne primes have a simple formula: 2n-1. In this case, "n" is equal to 82,589,933, which is itself a prime number. If you do the math, the new largest-known prime is a whopping 24,862,048 digits long.

We would write the number out for you, but it would fill up thousands of pages, give or take, and look like this gigantic zip file.

The latest Mersenne prime comes courtesy of a project started in 1996 called the Great Internet Mersenne Prime Search, in which people download special software that runs in the background on their computers. A computer owned by Patrick Laroche of Ocala, Fla., discovered the number on Dec. 7, and mathematicians have spent the past two weeks verifying the calculations. It's more than a million and a half digits longer than the previous largest known prime, discovered about a year ago by a computer in Germantown, Tenn.

Why should you care about Mersenne primes? They've proven useful in generating reasonably random numbers, but the best answer might be simply because they're there — and they're majestic.

Chris Caldwell, a mathematician at the University of Tennessee, Martin, talked to NPR in 2009 about these large primes.

"Mersennes, in a way, are kind of like a large diamond," Caldwell said back in 2009. Think about the Hope Diamond, a 45.52-carat diamond that sits in a special case in the Smithsonian National Museum of Natural History, usually with crowds around it.

"Nobody there looking at the Hope Diamond ever asks, 'Why did they bother to dig it up?' or 'What is it good for?' — even though it really isn't good for much other than to just hang there and people to look at," Caldwell said. "And in many ways, the Mersennes play that same role — that they really are the jewels of number theory."
The Great Internet Mersenne Prime Search announces the discovery of the latest largest known prime number, a Mersenne prime with 23,249,425 digits equal to 277,232,917 − 1.