Evil number

A kind of number

About Evil number

An evil number is a non-negative integer that has an even number of 1s in its binary expansion. The name is a wordplay on "even" (e.g. 3 = 11₂ has two 1s).

Key features

  • 0 is evil (zero 1s).
  • Odious numbers are those with an odd number of 1s in binary.

Examples:

0, 3, 5, 6, 9, 10, 12, 15

Further reading