A note on square totients
  A well-known conjecture asserts that there are infinitely many primes $p$ for which $p - 1$ is a perfect square. We obtain upper and lower bounds of matching order on the number of pairs of distinct primes $p,q \le x$ for which $(p - 1)(q - 1)$ is a perfect square. 
Tristan Freiberg and Carl Pomerance
math.NT