This is a PRP value of the Ramanujan Tau function.
Number of the form Tau(p^(q-1)), where p,q are odd primes.

http://mathworld.wolfram.com/TauFunctionPrime.html

Checked with PFGW (v3.7.8) in all odd prime bases < 20, and with Pari/GP (v2.5.5) implementation of BPSW.

To be completed...