600 B
600 B
Euler's Totient function, phi(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, phi(9)=6.
The number 1 is considered to be relatively prime to every positive number, so phi(1)=1.
Interestingly, phi(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 phi(n) is a permutation of n and the ratio n/phi(n) produces a minimum.