Source: wikibot/highly-totient-number
= Highly totient number
{wiki=Highly_totient_number}
A Highly Totient Number is a positive integer \\( n \\) for which the equation \\\[ \\Phi(\\Phi(\\Phi(... \\Phi(n)...))) = 1 \\\] holds true after applying the Euler's totient function \\( \\Phi \\) repeatedly a positive number of times. The Euler's totient function \\( \\Phi(n) \\) counts the number of positive integers up to \\( n \\) that are relatively prime to \\( n \\).