Using GCD sums, we show that the set of the primes has small common multiplicative energy with an arbitrary exponentially big integer set $S$ and, in particular, size of any arithmetic progression in $S$ having the beginning at zero, is at most $O(\log |S| \cdot \log \log |S|)$. This result can be considered as an integer analogue of Vinogradov's question about the least quadratic non--residue. The proof rests on a certain repulsion property of the function $f(x)=\log x$. Also, we consider the case of general $k$--convex functions $f$ and obtain a new incidence result for collections of the curves $y=f(x)+c$.