A sphenic number is a positive integer which is the product of exactly
three distinct primes. The first few sphenic numbers
are 30, 42, 66, 70, 78, 102, 105, 110, 114, ... (OEIS A007304).

In particular, if ,
, and are prime numbers, then every
sphenic number
has precisely eight positive divisors, namely , ,
, , ,
, , and itself.