11713771

This number is a prime.

Just showing those entries submitted by 'Beedassy': (Click here to show all)

The prime whose reversal factors into the two extremal primes with only the four prime digits: 17731711 = 2357*7523. Note that the latter primes concatenate to another prime (23577523) that remains a prime when each digit is replaced by its complement (87533587). [Beedassy]