Number Gossip

(Enter a number and I'll tell you everything you wanted to know about it but were afraid to ask.)

Unique Properties of 12

  • 12 is the smallest abundant number
  • 12 is the kissing number in three dimensions
  • There are 12 pentominos, the polyominoes made from 5 squares
  • 12 is the only number such that it is equal to the sum of 3 raised to its digits: 12 = 31 + 32
  • 12 is the smallest number such that it is equal to the sum of its digits plus the cubes of its digits: 12 = 1 + 2 + 13 + 23
  • Web pages about 12:
  • 12 is the weight of the modular discriminant as a modular form (submitted by Qiaochu Yuan)

Rare Properties of 12

Pentagonal
Pronic (Heteromecic)

Common Properties of 12

Abundant
Composite
Even
Evil
Practical