9

This number is a composite.

Just showing those entries submitted by 'Silva': (Click here to show all)

The first digit to appear as an end-digit in two consecutive primes (139 and 149). [Silva]

The only composite digit that can appear as end-digit of a prime. [Silva]

The only non-prime digit that is the difference of consecutive squares. [Silva]

The composite digit which first appears in a prime. [Silva]