666

This number is a composite.

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

666 is the largest three-digit repdigit such that the product of itself and all truncations of itself plus one is prime. I.e., 666*66*6 + 1 is prime. [Opao]

The first beastly gap between consecutive twin prime pairs occurs between {774131, 774133} and {774797, 774799}. [Opao]