# 75

This number is a composite.

75 is the smallest non-prime deficient number whose sum as well as product of aliquot divisors is a perfect square. [Gupta]

The first integer n such that the absolute value of the form n-2^k creates eight primes for eight successive values of k. Can you find another number with the same property? [Loungrides]

(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