What are the divisors of 1669?

1, 1669

There is a total of 2 positive divisors.
The sum of these divisors is 1670.
The arithmetic mean is 835.

2 odd divisors

1, 1669

How to compute the divisors of 1669?

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 1669 by each of the numbers from 1 to 1669 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)

1669 / 1 = 1669 (the remainder is 0, so 1 is a divisor of 1669)
1669 / 2 = 834.5 (the remainder is 1, so 2 is not a divisor of 1669)
1669 / 3 = 556.33333333333 (the remainder is 1, so 3 is not a divisor of 1669)
...
1669 / 1668 = 1.0005995203837 (the remainder is 1, so 1668 is not a divisor of 1669)
1669 / 1669 = 1 (the remainder is 0, so 1669 is a divisor of 1669)

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 1669 (i.e. 40.853396431631). 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 $\frac{N}{d} = D$ )

1669 / 1 = 1669 (the remainder is 0, so 1 and 1669 are divisors of 1669)
1669 / 2 = 834.5 (the remainder is 1, so 2 is not a divisor of 1669)
1669 / 3 = 556.33333333333 (the remainder is 1, so 3 is not a divisor of 1669)
...
1669 / 39 = 42.794871794872 (the remainder is 31, so 39 is not a divisor of 1669)
1669 / 40 = 41.725 (the remainder is 29, so 40 is not a divisor of 1669)