Euler's Totient Theorem
Euler's Totient Theorem is a theorem closely related to his function of the same name.
Theorem
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.