---
tag: 060ZX7C32T
kind: concept
name: Carmichael number
msc: [11A51]
sources:
  - url: https://en.wikipedia.org/wiki/Carmichael_number
    locator: lead section
same_as:
  wikidata: Q849530
  wikipedia: Carmichael number
---

## Summary

A Carmichael number is a composite number $n$ that satisfies $a^{n-1} \equiv 1 \pmod n$ for each integer $a$ coprime to $n$.
The [[definition of a Carmichael number|0TA7WT68RK]] gives the precise form.