245

This number is a composite.

The number 245*2^9+1 is a Proth prime. [Patterson]

245, 246, and 247 are the smallest three consecutive composite numbers whose concatenations of prime factors in ascending order (577, 2341, and 1319) are prime numbers. [Gaydos]

The expression 1*3*5*7*11*13*15*...*243*245 +/-2 produces the third and largest known pair (241-digits each) of "cousin" primes (that differ by 4) of this type. [Rivera]