What are the divisors of 5559?

1, 3, 17, 51, 109, 327, 1853, 5559

There is a total of 8 positive divisors.
The sum of these divisors is 7920.
The arithmetic mean is 990.

8 odd divisors

1, 3, 17, 51, 109, 327, 1853, 5559

How to compute the divisors of 5559?

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 5559 by each of the numbers from 1 to 5559 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)

5559 / 1 = 5559 (the remainder is 0, so 1 is a divisor of 5559)
5559 / 2 = 2779.5 (the remainder is 1, so 2 is not a divisor of 5559)
5559 / 3 = 1853 (the remainder is 0, so 3 is a divisor of 5559)
...
5559 / 5558 = 1.0001799208348 (the remainder is 1, so 5558 is not a divisor of 5559)
5559 / 5559 = 1 (the remainder is 0, so 5559 is a divisor of 5559)

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 5559 (i.e. 74.558701705435). 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 $\frac{N}{d} = D$ )

5559 / 1 = 5559 (the remainder is 0, so 1 and 5559 are divisors of 5559)
5559 / 2 = 2779.5 (the remainder is 1, so 2 is not a divisor of 5559)
5559 / 3 = 1853 (the remainder is 0, so 3 and 1853 are divisors of 5559)
...
5559 / 73 = 76.150684931507 (the remainder is 11, so 73 is not a divisor of 5559)
5559 / 74 = 75.121621621622 (the remainder is 9, so 74 is not a divisor of 5559)