A number made by multiplying exactly two prime numbers.

Example: 3 × 7 = 21

3 and 7 are prime numbers, so 21 is semiprime

Example: 2 × 2 = 4

2 is prime, so 4 is semiprime (it is OK to multiply the same prime number)

A number made by multiplying exactly two prime numbers.

Example: 3 × 7 = 21

3 and 7 are prime numbers, so 21 is semiprime

Example: 2 × 2 = 4

2 is prime, so 4 is semiprime (it is OK to multiply the same prime number)

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