999

This number is a composite.

The minimum sum of three 3-digit primes taken from a zeroless pandigital number (149 + 263 + 587 = 999).

999 can be written as the sum of three consecutive cuban primes (271 + 331 + 397). [Silva]

The sum of the 999 primes after 999 is prime. [Bopardikar]