Verified by LLR (strong-Fermat, Lucas and Frobenius PRP)

This number is the 13386th "base 21 minimal prime" as described on http://primes.utm.edu/glossary/xpage/MinimalPrime.html if we only count the primes > base, see https://github.com/xayahrainie4793/minimal-elements-of-the-prime-numbers for more information.

To be completed...