I asked this question one month Ago in MSE but no answer for existence of argument which show if such counter example exists we would have infinity of them or just finitely many examples
Lehmer's totient problem asks whether there is any composite number $n$ such that Euler's totient function $φ(n)$ divides $n − 1$. which it is unsolved problem or we may reformulate that question as : if $φ(n)$ divides $n − 1$ then $n$ must be a prime , Now my question here is :if a such counter example exists for Lehmer's totient problem could we prove that there are infinity of them or just finitely of them ?
