... and a prime multiplied by a prime is not a prime.
(divisors* greater than this value are not required
since "prime/noprime" is known by this time)
* 3,7,9,11,13,17,19,21,23,27,29,31,33,37, ... (ending 1,3,7,9 only)
414267891265733 = 1352921 × 306202573
sqrt(n)/4 = 5088392.988..
2345678991265733 = 11596969 × 202266557
sqrt(n)/4 = 12108052.566..
Rod