324

324 is a natural number that follows 323 and precedes 325. In mathematics, it is the square of 18, with prime factorization 2^2 × 3^4. It is a composite number with 15 positive divisors: 1, 2, 3, 4, 6, 9, 12, 18, 27, 36, 54, 81, 108, 162, 324. The sum of its digits is 9, and 324 is divisible by 9, making it a Harshad number in base 10. It lies between two consecutive squares, 17^2 = 289 and 19^2 = 361.

324 CE was a year in the Roman Empire during the reign of Constantine the Great. In that year Constantine defeated Licinius at the Battle of Chrysopolis, and by the following year he had become the sole ruler of the Eastern and Western Roman Empires. The year 325 saw the preparations for the First Council of Nicaea, which established the Nicene Creed and shaped early Christian doctrine.

324 is also the designation of a large main-belt asteroid, 324 Bamberga, which was discovered in 1892 by Max Wolf. It is among the brighter asteroids and orbits the Sun in the main asteroid belt between Mars and Jupiter.

In Roman numerals, 324 is written as CCCXXIV.