Dear gmp developer,

Found non-prime with method mpz_nextprime:

GMP Version 4.31(probably)
Compiled into a 64bit windows DLL

p = 2028576353201;
mpz_nextprime(p, p); // this will find 2028576353203 which is not prime.
I assume the number of repetitions for the probablyprime test inside 
mpz_nextprime() is too low. Probablyprime with 5 repetitions say its probably a 
prime, 6 repetitions already find this number is not a prime. Suggestion would 
be increase the number of repetitions from about 5 to about 7..20? And add an 
overload where one can specify number of repetitions? (Some apps need speed, 
some need certainity.)
Or add 2028576353203 (and the number of repetitions) to documentation of 
mpz_nextprime().

Best Regards,
Simon Cavegn

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