# Is 123 a prime number?

It is possible to find out using mathematical methods whether a given integer is a prime number or not.

For 123, the answer is: No, 123 is not a prime number.

The list of all positive divisors (i.e., the list of all integers that divide 123) is as follows: 1, 3, 41, 123.

For 123 to be a prime number, it would have been required that 123 has only two divisors, i.e., itself and 1.

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As a consequence:

For 123 to be a prime number, it would have been required that 123 has only two divisors, i.e., itself and 1.

However, 123 is a **semiprime** (also called biprime or 2-almost-prime), because it is the product of a two non-necessarily distinct prime numbers. Indeed, 123 = 3 x 41, where 3 and 41 are both prime numbers.

### Is 123 a deficient number?

Yes, 123 is a deficient number, that is to say 123 is a natural number that is strictly larger than the sum of its proper divisors, i.e., the divisors of 123 without 123 itself (that is 1 + 3 + 41 = 45).