324 = 22 x 34.
324 is a perfect square: 324 = 182.
324 is the smallest untouchable square. Untouchable numbers are those that are not the sum of the proper divisors of any number.
324 is the largest possible product of positive integers with sum 16.
324 Bamberga, discovered in 1892, is one of the largest asteroids in the main belt.
Source: Number Gossip