This number is a composite.

+ The sum of digits ± 1 and the product ± 1 of 213 is prime. Note the sum of the digits is the same as the product. [Russo]

(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