4659775785220018543264560743076778192897

p40 = 4659775785220018543264560743076778192897 is a prime number.

This can be verified from the factorization

p40 - 1 = 212 . 3 . 5639 . 8231 . 433639 . 18840862799165386003967

The fact that p40 - 1 is divisible by 212 is not surprising, since p40 is a factor of the Fermat number F10.

Richard Brent
26 October 1995