What are the divisors of 3929?

1, 3929

There is a total of 2 positive divisors.
The sum of these divisors is 3930.
The arithmetic mean is 1965.

2 odd divisors

1, 3929

How to compute the divisors of 3929?

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 3929 by each of the numbers from 1 to 3929 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)

3929 / 1 = 3929 (the remainder is 0, so 1 is a divisor of 3929)
3929 / 2 = 1964.5 (the remainder is 1, so 2 is not a divisor of 3929)
3929 / 3 = 1309.6666666667 (the remainder is 2, so 3 is not a divisor of 3929)
...
3929 / 3928 = 1.0002545824847 (the remainder is 1, so 3928 is not a divisor of 3929)
3929 / 3929 = 1 (the remainder is 0, so 3929 is a divisor of 3929)

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 3929 (i.e. 62.681735776859). 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 $\frac{N}{d} = D$ )

3929 / 1 = 3929 (the remainder is 0, so 1 and 3929 are divisors of 3929)
3929 / 2 = 1964.5 (the remainder is 1, so 2 is not a divisor of 3929)
3929 / 3 = 1309.6666666667 (the remainder is 2, so 3 is not a divisor of 3929)
...
3929 / 61 = 64.409836065574 (the remainder is 25, so 61 is not a divisor of 3929)
3929 / 62 = 63.370967741935 (the remainder is 23, so 62 is not a divisor of 3929)