biprime | pq-number

A semiprime, also called a 2-almost prime, biprime , or p q-number, is a composite number that is the product of two (possibly equal) primes. The first few are 4, 6, 9, 10, 14, 15, 21, 22, ... (OEIS A001358). The first few semiprimes whose factors are distinct (i.e., the squarefree semiprimes) are 6, 10, 14, 15, 21, 22, 26, 33, 34, ... (OEIS A006881). The square of any prime number is by definition a semiprime. The largest known semiprime is therefore the square of the largest known prime.

almost prime | Chen's theorem | composite number | emirpimes | greatest prime factor | highly composite number | Jevons' number | Landau's problems | large number | prime factor | prime factorization | prime number | rough number | round number | RSA encryption | RSA number | smooth number | sphenic number