133 (number)

Template:Infobox number 133 (one hundred [and] thirty-three) is the natural number following 132 and preceding 134.

In mathematics

133 is an n whose divisors (excluding n itself) added up divide φ(n). It is an octagonal number<ref>{{#invoke:citation/CS1|citation |CitationClass=web }}</ref> and a happy number.<ref>{{#invoke:citation/CS1|citation |CitationClass=web }}</ref>

133 is a Harshad number, because it is divisible by the sum of its digits.

133 is a repdigit in base 11 (111) and base 18 (77), whilst in base 20 it is a cyclic number formed from the reciprocal of the number three.

133 is a semiprime: a product of two prime numbers, namely 7 and 19. Since those prime factors are Gaussian primes, this means that 133 is a Blum integer.

133 is the number of compositions of 13 into distinct parts.<ref>Template:Cite OEIS</ref>

133 is the 100th composite number.