21462...98751 (43009-digits)
This number is a prime.
12291*2^142857-1 is prime.
Note that 12291 written in base-4 is palindromic (3000003).
Also, if you sum the factorials of the digits of
12291*2^142857-1 you get the prime 1767235343. [Earls]
Printed from the PrimePages <t5k.org> © G. L. Honaker and Chris K. Caldwell