Pillai showedshowed in 1929 that the function $A(n)$ giving the number solutions of the equation $\phi(x)=n$ is unbounded in this paper (S. Pillai , On some functions connected with φ(n) On some functions connected with $\varphi(n)$, Bull. Amer. Math. Soc. 35 (1929), 832–836),. I'm interested to know a few about Bound of solutions about bounds on solutions of this equation $\phi(x)=n!$ which it is assigned this sequenceA055506 in OEIS , In A055506where it wereis claimed that if $\phi(x) = n!$, then $x$ must be a product of primes $p$ such that $p - 1$ divides $n!$ but this still. It is unclear to meme if this gives toallows me any validity to prove that there are finitely many solutions of the equation $\phi(x) = n!$ or not .Now I want to know if $\phi(x)=n!$ have finitely many solutions or not ? probably the same meaning of this Probably an equivalent question is to ask :Does is the number of solutions of $\phi(x)=n!$ bounded ?if If yes, what is its bound ?
Related question: (https://math.stackexchange.com/q/3747571/156150)