What are the divisors of 2123?

1, 11, 193, 2123

There is a total of 4 positive divisors.
The sum of these divisors is 2328.
The arithmetic mean is 582.

4 odd divisors

1, 11, 193, 2123

How to compute the divisors of 2123?

A number N is said to be divisible by a number M (with M non-zero) if, when we divide N by M, the remainder of the division is zero.

$N mod M = 0$

Brute force algorithm

We could start by using a brute-force method which would involve dividing 2123 by each of the numbers from 1 to 2123 to determine which ones have a remainder equal to 0.

$Remainder = N - (M \times ⌊ \frac{N}{M} ⌋)$

(where $⌊ \frac{N}{M} ⌋$ is the integer part of the quotient)

2123 / 1 = 2123 (the remainder is 0, so 1 is a divisor of 2123)
2123 / 2 = 1061.5 (the remainder is 1, so 2 is not a divisor of 2123)
2123 / 3 = 707.66666666667 (the remainder is 2, so 3 is not a divisor of 2123)
...
2123 / 2122 = 1.0004712535344 (the remainder is 1, so 2122 is not a divisor of 2123)
2123 / 2123 = 1 (the remainder is 0, so 2123 is a divisor of 2123)

Improved algorithm using square-root

However, there is another slightly better approach that reduces the number of iterations by testing only integers less than or equal to the square root of 2123 (i.e. 46.076024134033). Indeed, if a number N has a divisor D greater than its square root, then there is necessarily a smaller divisor d such that:

$D \times d = N$

(thus, if $\frac{N}{D} = d$ , then $\frac{N}{d} = D$ )

2123 / 1 = 2123 (the remainder is 0, so 1 and 2123 are divisors of 2123)
2123 / 2 = 1061.5 (the remainder is 1, so 2 is not a divisor of 2123)
2123 / 3 = 707.66666666667 (the remainder is 2, so 3 is not a divisor of 2123)
...
2123 / 45 = 47.177777777778 (the remainder is 8, so 45 is not a divisor of 2123)
2123 / 46 = 46.152173913043 (the remainder is 7, so 46 is not a divisor of 2123)