What are the divisors of 2117?

1, 29, 73, 2117

There is a total of 4 positive divisors.
The sum of these divisors is 2220.
The arithmetic mean is 555.

4 odd divisors

1, 29, 73, 2117

How to compute the divisors of 2117?

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 2117 by each of the numbers from 1 to 2117 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)

2117 / 1 = 2117 (the remainder is 0, so 1 is a divisor of 2117)
2117 / 2 = 1058.5 (the remainder is 1, so 2 is not a divisor of 2117)
2117 / 3 = 705.66666666667 (the remainder is 2, so 3 is not a divisor of 2117)
...
2117 / 2116 = 1.0004725897921 (the remainder is 1, so 2116 is not a divisor of 2117)
2117 / 2117 = 1 (the remainder is 0, so 2117 is a divisor of 2117)

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 2117 (i.e. 46.010868281309). 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 $\frac{N}{d} = D$ )

2117 / 1 = 2117 (the remainder is 0, so 1 and 2117 are divisors of 2117)
2117 / 2 = 1058.5 (the remainder is 1, so 2 is not a divisor of 2117)
2117 / 3 = 705.66666666667 (the remainder is 2, so 3 is not a divisor of 2117)
...
2117 / 45 = 47.044444444444 (the remainder is 2, so 45 is not a divisor of 2117)
2117 / 46 = 46.021739130435 (the remainder is 1, so 46 is not a divisor of 2117)