# 217

This number is a composite.

217 is the smallest odd pseudoprime base five.

47 and 89 are primes, as is their concatenation (4789). Inserting the lowly 0 between them transforms the prime into a power, i.e. 47089, the square of 217. [Trotter]

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