semiprime number

A **semiprime number** is a natural number that is the product of exactly two prime numbers. These two primes can be the same (making the semiprime a square of a prime) or different. Semiprimes play an important role in number theory and cryptography, particularly in encryption algorithms like RSA, where the difficulty of factoring large semiprime numbers ensures security. Examples of semiprime numbers include 6 (2 × 3), 9 (3 × 3), and 15 (3 × 5).