204 205 → Factorization 2× 3 × 17 | Cardinal two hundred four Roman numeral CCIV | |
Ordinal 204th(two hundred and fourth) Divisors 1, 2, 3, 4, 6, 12, 17, 34, 51, 68, 102, 204 | ||
204 (two hundred [and] four) is the natural number following 203 and preceding 205.
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In mathematics
204 is a refactorable number. 204 is a square pyramidal number: 204 balls may be stacked in a pyramid whose base is an 8 × 8 square. Its square, 2042 = 41616, is the fourth square triangular number. As a figurate number, 204 is also a nonagonal number and a truncated triangular pyramid number. 204 is a member of the Mian-Chowla sequence.
There are exactly 204 irreducible quintic polynomials over a four-element field, exactly 204 ways to place three non-attacking chess queens on a 5 × 5 board, exactly 204 squares of an infinite chess move that are eight knight's moves from the center, exactly 204 strings of length 11 over a three-letter alphabet with no consecutively-repeated substring, and exactly 204 ways of immersing an oriented circle into the oriented plane so that it has four double points.
Both 204 and its square are sums of a pair of twin primes: 204 = 101 + 103 and 2042 = 41616 = 20807 + 20809. The only smaller numbers with the same property are 12 and 84.