Factors of 399
The factors of 399 are 1, 3, 7, 19, 21, 57, 133, 399. It has 8 factors.
Factors of 399
Pick any whole number from 1 to 10,000.
How to work it out
- 1
A factor of 399 is a whole number that divides it with nothing left over. You only need to test the numbers up to √399 ≈ 19.97; every one that divides gives a pair.
- 2
The factor pairs are listed in the table below. Together they give 8 factors.
- 3
Prime factorisation: keep dividing by the smallest prime that fits.
- 4
Add all the factors: 1 + 3 + 7 + 19 + 21 + 57 + 133 + 399 = 640. Without 399 itself that is 241, so 399 is a deficient number.
LaTeX source of the formulas on this page
\[ 399 = 3 \times 7 \times 19 \]
Factor pairs of 399
| Factor | Pairs with | Product |
|---|---|---|
| 1 | 399 | 1 × 399 = 399 |
| 3 | 133 | 3 × 133 = 399 |
| 7 | 57 | 7 × 57 = 399 |
| 19 | 21 | 19 × 21 = 399 |
Questions
What are the factors of 399?
The factors of 399 are 1, 3, 7, 19, 21, 57, 133, 399. It has 8 factors.
What are the prime factors of 399?
3, 7, 19. As a product: 3 × 7 × 19.
How many factors does 399 have?
399 has 8 factors (4 factor pairs).
What is the sum of the factors of 399?
640.
Is 399 a prime number?
No. It is divisible by 3, so 399 = 3 × 133.