What are the divisors of 1654?

1, 2, 827, 1654

There is a total of 4 positive divisors.
The sum of these divisors is 2484.
The arithmetic mean is 621.

2 even divisors

2, 1654

2 odd divisors

1, 827

How to compute the divisors of 1654?

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 1654 by each of the numbers from 1 to 1654 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)

1654 / 1 = 1654 (the remainder is 0, so 1 is a divisor of 1654)
1654 / 2 = 827 (the remainder is 0, so 2 is a divisor of 1654)
1654 / 3 = 551.33333333333 (the remainder is 1, so 3 is not a divisor of 1654)
...
1654 / 1653 = 1.0006049606776 (the remainder is 1, so 1653 is not a divisor of 1654)
1654 / 1654 = 1 (the remainder is 0, so 1654 is a divisor of 1654)

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 1654 (i.e. 40.669398815326). 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 $\frac{N}{d} = D$ )

1654 / 1 = 1654 (the remainder is 0, so 1 and 1654 are divisors of 1654)
1654 / 2 = 827 (the remainder is 0, so 2 and 827 are divisors of 1654)
1654 / 3 = 551.33333333333 (the remainder is 1, so 3 is not a divisor of 1654)
...
1654 / 39 = 42.410256410256 (the remainder is 16, so 39 is not a divisor of 1654)
1654 / 40 = 41.35 (the remainder is 14, so 40 is not a divisor of 1654)