Is 20 a prime number?
No, 20 is not a prime number. It is divisible by 2: 20 = 2 × 10.
Is 20 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 √20 ≈ 4.47. If none of them divides 20, it is prime.
- 3
2 divides 20 exactly, so it is not prime. Its prime factorisation is
LaTeX source of the formulas on this page
\[ 20 = 2^{2} \times 5 \]Testing 20 by the primes up to its square root
| Prime | Division | Result |
|---|---|---|
| 2 | 20 ÷ 2 | divides exactly (10) |
| 3 | 20 ÷ 3 | leaves 2 |
Questions
Is 20 a prime number?
No, 20 is not a prime number. It is divisible by 2: 20 = 2 × 10.
What is the next prime after 20?
23.
What is the prime number before 20?
19.
What are the factors of 20?
1, 2, 4, 5, 10, 20.