138 = 2 x 3 x 23.
138 is the smallest possible product of 3 primes, one of which is the concatenation of the other two.
138 is a value of n for which n!!! - 1 is prime.
12 × 483 = 5,796 = 42 × 138.
NGC-138 is a spiral galaxy in the constellation Pisces.
Source: Number Gossip
