Erdős problem 416

Let V(x) count the number of n≤x such that ϕ(m)=n is solvable. V(x)=x/logx * e^((C+o(1))(log log log x)^2), for some explicit constant C>0. Ref:Maier, Helmut and Pomerance, Carl, _On the number of distinct values of Euler's $\phi$-function_.