---
id: 5900f3b21000cf542c50fec5
challengeType: 5
title: 'Problem 70: Totient permutation'
---
## Description
Euler's Totient function, φ(n) [sometimes called the phi function], is used to determine the number of positive numbers less than or equal to n which are relatively prime to n. For example, as 1, 2, 4, 5, 7, and 8, are all less than nine and relatively prime to nine, φ(9)=6.The number 1 is considered to be relatively prime to every positive number, so φ(1)=1.
Interestingly, φ(87109)=79180, and it can be seen that 87109 is a permutation of 79180.
Find the value of n, 1 < n < 107, for which φ(n) is a permutation of n and the ratio n/φ(n) produces a minimum.
## Instructions
## Tests
```yml
tests:
- text: euler70() should return 8319823.
testString: assert.strictEqual(euler70(), 8319823, 'euler70() should return 8319823.');
```
## Challenge Seed
```js
function euler70() {
// Good luck!
return true;
}
euler70();
```