31111...11113 (127-digits)
This number is a prime.
3111111 1111111111 1111111111 1111111111 1111111111 1111111111
1111111111 1111111111 1111111111 1111111111 1111111111 1111111111 1111111113
This the 5th number of this form. Note that it has a Mersenne prime number of digits and a palindromic prime digital sum. [Patterson]
Printed from the PrimePages <t5k.org> © G. L. Honaker and Chris K. Caldwell