123479
This number is a prime.
The product of the first n digits of 123479 (read left-to-right) is either one less or one more than a prime.
The smallest prime formed from all of the positive digits
that are expressible as sum of two triangular numbers in
exactly one way. [Honaker]
(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