## Totient permutation

### Problem 70

Published on Friday, 21st May 2004, 06:00 pm; Solved by 13442; Difficulty rating: 20%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` < 10^{7}, for which φ(`n`) is a permutation of `n` and the ratio `n`/φ(`n`) produces a minimum.