use 5.012;
use warnings;
use Math::GMPz qw(:mpz );
use Digest::SHA qw(sha512_hex);

my $sha = sha512_hex('password');
my $op = Rmpz_init_set_str($sha, 16);
my $rop = Rmpz_init2(512);
Rmpz_nextprime($rop, $op);
say Rmpz_get_str($rop, 16);