3581
This number is a prime.
The smallest prime p for which all the decimal digits of 31p are either zeros or ones (31 * 3581 = 111011). The next few primes of this type are 3583871, 32290681, 326132581, ... . [Keith]
(There is one curio for this number that has not yet been approved by an editor.)
Printed from the PrimePages <t5k.org> © G. L. Honaker and Chris K. Caldwell