1271

This number is a composite.

The smallest piculiar semiprime, i.e., a number that is the product of two primes whose concatenation (in some order) produce the decimal expansion of π, e.g., 1271 = 31*41. The sequence begins 1271, 42477, 128929, 628318, 424777960767, 12893722612807, 1289372261283590392341944873, 1289372261283590392341944881664589410107, ... . See largest known.