Fast · Free · Online
Euler totient (phi) calculator
Calculate Euler's totient: count positive integers up to the input that are coprime to it.
How to use this calculator
Replace with a positive integer. For , the coprime integers are .
Tap the math below to edit it and see the result. Once a result is ready, press Tab on a hardware keyboard to accept it. Outside a matrix, Return completes the line; the phone math keyboard has the same Return action.
Try it here
Interactive tools require JavaScript. You can read the guide and example without it.
What to know
Euler's totient is different from the golden ratio and the normal-distribution CDF. Large inputs may time out.
Mathlean combines visual mathematical input with computation and canvas tools. Results depend on the expression and available engine support; check important answers independently.