📂Number Theory

Semi-prime

Definition

Two product of prime numbers is called a Semiprime.

Description

Examples of semiprimes include $4 = 2 \cdot 2$, $21 = 3 \cdot 7$, $673703 = 719 \cdot 937$, etc.

In Japanese translation, it is also called 半素数 but it is hard to find either semiprime or 半素数 in the Korean documents.

Essentially, semiprime is not a semiprime itself, but it somewhat inherits the properties of prime numbers and is applied. For example, if you make a semiprime by multiplying two rather large prime numbers, its prime factorization is quite difficult. The difficulty of this prime factorization problem is exactly what the RSA cryptosystem uses.