---
tag: 0DAMHCT17R
kind: concept
name: Euler's totient function
msc: [11A25]
sources:
  - url: https://en.wikipedia.org/wiki/Euler%27s_totient_function
    locator: lead section
same_as:
  wikidata: Q190026
  wikipedia: Euler's totient function
---

## Summary

Euler's totient function $\varphi$ gives, for each positive integer $n$, the number of integers from $1$ to $n$ that are coprime to $n$.
The [[definition of Euler's totient function|0VV04M41AN]] gives the precise form.