What are the divisors of 4485?

1, 3, 5, 13, 15, 23, 39, 65, 69, 115, 195, 299, 345, 897, 1495, 4485

There is a total of 16 positive divisors.
The sum of these divisors is 8064.
The arithmetic mean is 504.

16 odd divisors

1, 3, 5, 13, 15, 23, 39, 65, 69, 115, 195, 299, 345, 897, 1495, 4485

How to compute the divisors of 4485?

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 4485 by each of the numbers from 1 to 4485 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)

4485 / 1 = 4485 (the remainder is 0, so 1 is a divisor of 4485)
4485 / 2 = 2242.5 (the remainder is 1, so 2 is not a divisor of 4485)
4485 / 3 = 1495 (the remainder is 0, so 3 is a divisor of 4485)
...
4485 / 4484 = 1.000223015165 (the remainder is 1, so 4484 is not a divisor of 4485)
4485 / 4485 = 1 (the remainder is 0, so 4485 is a divisor of 4485)

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 4485 (i.e. 66.970142601013). 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 $\frac{N}{d} = D$ )

4485 / 1 = 4485 (the remainder is 0, so 1 and 4485 are divisors of 4485)
4485 / 2 = 2242.5 (the remainder is 1, so 2 is not a divisor of 4485)
4485 / 3 = 1495 (the remainder is 0, so 3 and 1495 are divisors of 4485)
...
4485 / 65 = 69 (the remainder is 0, so 65 and 69 are divisors of 4485)
4485 / 66 = 67.954545454545 (the remainder is 63, so 66 is not a divisor of 4485)