In Int§

See primary documentation in context for routine is-prime

multi        is-prime (Int:D $number --> Bool:D)
multi method is-prime (Int:D: --> Bool:D)

Returns True if this Int is known to be a prime, or is likely to be a prime based on a probabilistic Miller-Rabin test.

Returns False if this Int is known not to be a prime.

say;         # OUTPUT: «True␤» 
say is-prime(9);        # OUTPUT: «False␤»