(PHP 5 >= 5.2.0, PHP 7, PHP 8)
gmp_nextprime — Find next prime number
Return the next prime number greater than num,
as a GMP number.
示例 #1 gmp_nextprime() example
<?php
$prime1 = gmp_nextprime(10); // next prime number greater than 10
$prime2 = gmp_nextprime(-1000); // next prime number greater than -1000
echo gmp_strval($prime1) . "\n";
echo gmp_strval($prime2) . "\n";
?>以上示例会输出：
11 2
注意:
This function uses a probabilistic algorithm to identify primes and chances to get a composite number are extremely small.