Is 400 a prime number?
No, 400 is not a prime number. It is divisible by 2: 400 = 2 × 200.
Is 400 prime?
Pick any whole number from 1 to 10,000.
How to work it out
- 1
A prime number has exactly two factors: 1 and itself.
- 2
It is enough to test the primes up to √400 ≈ 20.00. If none of them divides 400, it is prime.
- 3
2 divides 400 exactly, so it is not prime. Its prime factorisation is
LaTeX source of the formulas on this page
\[ 400 = 2^{4} \times 5^{2} \]Testing 400 by the primes up to its square root
| Prime | Division | Result |
|---|---|---|
| 2 | 400 ÷ 2 | divides exactly (200) |
| 3 | 400 ÷ 3 | leaves 1 |
| 5 | 400 ÷ 5 | divides exactly (80) |
| 7 | 400 ÷ 7 | leaves 1 |
| 11 | 400 ÷ 11 | leaves 4 |
| 13 | 400 ÷ 13 | leaves 10 |
| 17 | 400 ÷ 17 | leaves 9 |
| 19 | 400 ÷ 19 | leaves 1 |
Questions
Is 400 a prime number?
No, 400 is not a prime number. It is divisible by 2: 400 = 2 × 200.
What is the next prime after 400?
401.
What is the prime number before 400?
397.
What are the factors of 400?
1, 2, 4, 5, 8, 10, 16, 20, 25, 40, 50, 80, 100, 200, 400.