among the numbers 1 to 6 the numbers 2 3 and 5 are the prime numbers while 1 4 and 6 are not prime 1 is excluded as a prime number for reasons explained below 2 is a prime number since the only natural numbers dividing it are 1 and 2ence 6 is not prime the image at the right illustrates that 12 is not prime 12 3 4 no even number greater than 2 is prime because by definition any such number n has at least three distinct divisors namely 1 2 and n this implies that n is not prime