Is 1643 a prime number?
No, 1643 is not a prime number. It is divisible by 31: 1643 = 31 × 53.
Is 1643 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 √1643 ≈ 40.53. If none of them divides 1643, it is prime.
- 3
31 divides 1643 exactly, so it is not prime. Its prime factorisation is
LaTeX source of the formulas on this page
\[ 1643 = 31 \times 53 \]
Testing 1643 by the primes up to its square root
| Prime | Division | Result |
|---|---|---|
| 2 | 1643 ÷ 2 | leaves 1 |
| 3 | 1643 ÷ 3 | leaves 2 |
| 5 | 1643 ÷ 5 | leaves 3 |
| 7 | 1643 ÷ 7 | leaves 5 |
| 11 | 1643 ÷ 11 | leaves 4 |
| 13 | 1643 ÷ 13 | leaves 5 |
| 17 | 1643 ÷ 17 | leaves 11 |
| 19 | 1643 ÷ 19 | leaves 9 |
| 23 | 1643 ÷ 23 | leaves 10 |
| 29 | 1643 ÷ 29 | leaves 19 |
| 31 | 1643 ÷ 31 | divides exactly (53) |
| 37 | 1643 ÷ 37 | leaves 15 |
Questions
Is 1643 a prime number?
No, 1643 is not a prime number. It is divisible by 31: 1643 = 31 × 53.
What is the next prime after 1643?
1657.
What is the prime number before 1643?
1637.
What are the factors of 1643?
1, 31, 53, 1643.