This number is a composite.

+ The only 2-sphenic number, (137953 = 29*67*71), that is a concatenation of double-digit primes (13, 79, 53) and at the same time consists of all the odd digits only. Note that the concatenation of its prime factors, i.e., 296771, is a prime and the sum of the same factors, i.e., 29+67+71=167, is an emirp. [Loungrides]

Printed from the PrimePages <t5k.org> © G. L. Honaker and Chris K. Caldwell