KnowraEuler's totient functionLinked fromLinked fromThe 21 pages that link to Euler's totient function, each with the reason it gives.All 21Broader topic 3Related 16Compared with 2Leonhard EulerBroader topic: Euler studied this counting function and established a theorem that links it to modular arithmetic.Multiplicative functionBroader topic: Coprime residue classes combine to give φ(ab)=φ(a)φ(b) when a and b are coprime.Arithmetic functionBroader topic: It measures how many residue classes modulo n are invertible.