What are the divisors of 2983?

1, 19, 157, 2983

There is a total of 4 positive divisors.
The sum of these divisors is 3160.
The arithmetic mean is 790.

4 odd divisors

1, 19, 157, 2983

How to compute the divisors of 2983?

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 2983 by each of the numbers from 1 to 2983 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)

2983 / 1 = 2983 (the remainder is 0, so 1 is a divisor of 2983)
2983 / 2 = 1491.5 (the remainder is 1, so 2 is not a divisor of 2983)
2983 / 3 = 994.33333333333 (the remainder is 1, so 3 is not a divisor of 2983)
...
2983 / 2982 = 1.0003353454058 (the remainder is 1, so 2982 is not a divisor of 2983)
2983 / 2983 = 1 (the remainder is 0, so 2983 is a divisor of 2983)

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 2983 (i.e. 54.616847217685). 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 $\frac{N}{d} = D$ )

2983 / 1 = 2983 (the remainder is 0, so 1 and 2983 are divisors of 2983)
2983 / 2 = 1491.5 (the remainder is 1, so 2 is not a divisor of 2983)
2983 / 3 = 994.33333333333 (the remainder is 1, so 3 is not a divisor of 2983)
...
2983 / 53 = 56.283018867925 (the remainder is 15, so 53 is not a divisor of 2983)
2983 / 54 = 55.240740740741 (the remainder is 13, so 54 is not a divisor of 2983)