Prime numbers are positive integers that are only divisible by itself and 1. The numbers 2,3,5,7…are all prime. The great Greek mathematician Euclid had proven that there are an infinite numbers of prime numbers as early as 300 B.C. Did you know that in the banking system most of the encryption are done using prime numbers. The largest prime number found so far is 257,885,161-1 which has 17,425,170 digits.