Semiprime

A semiprime is a composite number which has exactly 2 factors, and it is the product of 2 prime numbers.

Properties
Square numbers are not semiprimes.

Any multiple of a semiprime is not a semiprime.

Powers of any number are not semiprimes, as they have 3 or more factors, but they are multiples of the same number and not a semiprime. 8 may have 4 factors, but it is not a semiprime, as its only prime factor is 2.

There should be exactly 2 prime factors in a semiprime.

Prime numbers are not semiprimes as they have only 1 prime factor: itself.

Most semiprimes are even numbers.