What are the divisors of 1918?

1, 2, 7, 14, 137, 274, 959, 1918

There is a total of 8 positive divisors.
The sum of these divisors is 3312.
The arithmetic mean is 414.

4 even divisors

2, 14, 274, 1918

4 odd divisors

1, 7, 137, 959

How to compute the divisors of 1918?

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 1918 by each of the numbers from 1 to 1918 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)

1918 / 1 = 1918 (the remainder is 0, so 1 is a divisor of 1918)
1918 / 2 = 959 (the remainder is 0, so 2 is a divisor of 1918)
1918 / 3 = 639.33333333333 (the remainder is 1, so 3 is not a divisor of 1918)
...
1918 / 1917 = 1.000521648409 (the remainder is 1, so 1917 is not a divisor of 1918)
1918 / 1918 = 1 (the remainder is 0, so 1918 is a divisor of 1918)

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 1918 (i.e. 43.794976880916). 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 $\frac{N}{d} = D$ )

1918 / 1 = 1918 (the remainder is 0, so 1 and 1918 are divisors of 1918)
1918 / 2 = 959 (the remainder is 0, so 2 and 959 are divisors of 1918)
1918 / 3 = 639.33333333333 (the remainder is 1, so 3 is not a divisor of 1918)
...
1918 / 42 = 45.666666666667 (the remainder is 28, so 42 is not a divisor of 1918)
1918 / 43 = 44.604651162791 (the remainder is 26, so 43 is not a divisor of 1918)