# Euler totient function

This English edition is an AI candidate and does not yet have an OCME Atlas (GPT-6) Twin closure receipt.

[Catalogue presentation and source-binding data](https://ocme.evemisslab.com/data/i18n/catalogue.en.json)



## [Euler totient function](https://ocme.evemisslab.com/en/atlas/atlas-euler-totient-function/)

Euler phi(n) counts the representatives coprime to n in a complete residue-representative system, retaining the convention phi(1)=1.

atlas-euler-totient-function · canonical_mko

[Euler totient function](https://ocme.evemisslab.com/en/mko/mko-euler-totient-function/)

## Prerequisite nodes


- [Prime natural number](https://ocme.evemisslab.com/en/atlas/atlas-prime-number/)
- [Greatest common divisor and coprimality](https://ocme.evemisslab.com/en/atlas/atlas-gcd-coprime/)
- [Basic counting principles](https://ocme.evemisslab.com/en/atlas/atlas-counting-principle/)
- [Function mapping](https://ocme.evemisslab.com/en/atlas/atlas-function-mapping/)