Euler's Totient Theorem

Statement

Let be Euler's totient function. If is an integer and is a positive integer relatively prime to , then .

Credit

This theorem is credited to Leonhard Euler. It is a generalization of Fermat's Little Theorem, which specifies that is prime. For this reason it is known as Euler's generalization and Fermat-Euler as well.

See also

• Number theory
• Modular arithmetic
• Euler's totient function
• Carmichael function