168 (number)
# 168 (number)

168 (one hundred [and] sixty-eight) is the natural number following 167 and preceding 169.

## In mathematics

168 is an even number, a composite number, an abundant number, and an idoneal number.

There are 168 primes less than 1000. 168 is the product of the first two perfect numbers.

168 is the order of the group PSL(2,7), the second smallest nonabelian simple group.

From Hurwitz's automorphisms theorem, 168 is the maximum possible number of automorphisms of a genus 3 Riemann surface, this maximum being achieved by the Klein quartic, whose symmetry group is PSL(2,7). The Fano plane has 168 symmetries.

168 is the largest known n such that $2^n$ does not contain all decimal digits.

168 is the fourth Dedekind number.

## In astronomy

* 168P/Hergenrother is a periodic comet in the Solar System
* 168 Sibylla is a dark Main belt asteroid

## In the military

* Japanese submarine I-168 was an Imperial Japanese Navy Kaidai-class submarine during World War II
* USNS Catawba (T-ATF-168) is a United States Navy fleet tugboat
* USS Amick (DE-168) was a United States Navy Cannon-class destroyer escort during World War II
* USS Charlevoix (AK-168) was a United States Navy Alamosa-class cargo ship during World War II
* USS Gage (APA-168) was a United States Navy Haskell-class attack transport during World War II
* USS Maddox (DD-168) was a United States Navy Wickes-class destroyer during World War I
* USS Nautilus (SS-168) was a United States Navy Narwhal-class submarine during World War II
* USS Southland (IX-168) was a United States Navy steamer during World War II
* USS War Hawk (AP-168) was a La Salle-class transport during World War II

## In movies

* The 168 Film Project in Los Angeles

## In transportation

* New York City Subway stations
   * 168th Street (New York City Subway); a subway station complex at 168th Street and Broadway consisting of:
      * 168th Street (IRT Broadway – Seventh Avenue Line); serving the 1 train
      * 168th Street (IND Eighth Avenue Line); serving the A and ​C trains
   * 168th Street (BMT Jamaica Line); was the former terminal of the BMT Jamaica Line in Queens
* British Rail Class 168
* VASP Flight 168 from Rio de Janeiro, Brazil to Fortaleza; crashed on June 8, 1982

## In other fields

168 is also:

* The year AD 168 or 168 BC
* 168 AH is a year in the Islamic calendar that corresponds to 784 – 785 CE
* The number of hours in a week, or 7 x 24 hours
* In the game of dominoes, tiles are marked with a number of spots, or pips. The Double 6 set (28 tiles) totals 168 pips
* Tracy 168, a New York City graffiti artist
* Minuscule 168 is a Greek minuscule manuscript of the New Testament
* Some Chinese consider 168 a lucky number, because it is roughly homophonous with the phrase "一路發", which means "fortune all the way", or, as the United States Mint claims- "Prosperity Forever"
* 168 is the name of the most commonly used laboratory strain of Bacillus subtilis, a bacterium
