[bajwcdcu] Large, well-understood prime number

The largest 1024-bit prime number, i.e., the largest prime less than 2^1024, namely p=2^1024-105, has a fortuitously achievable by GMP ECM complete factorization of p-1 = 2 * 3 * 3 * 5 * 101 * 15583 * 7823375369 * 265057589941 * 4267405562517841 * 7746462444923356569692676551 * p236

Thence znprimroot(precprime(2^(2^10))) is 6.