Carmichael number

Named after Robert Daniel Carmichael (1879–1967), American mathematician.

Carmichael number (plural Carmichael numbers)

1. (mathematics) A composite number ${\displaystyle n}$ that satisfies the modular arithmetic congruence relation ${\displaystyle b^{n-1}\equiv 1{\pmod {n}}}$ for all integers ${\displaystyle 1<b<n}$ that are relatively prime to ${\displaystyle n}$.