Is 1243 a prime number?
No, 1243 is not a prime number. It is divisible by 11: 1243 = 11 × 113.
Is 1243 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 √1243 ≈ 35.26. If none of them divides 1243, it is prime.
- 3
11 divides 1243 exactly, so it is not prime. Its prime factorisation is
LaTeX source of the formulas on this page
\[ 1243 = 11 \times 113 \]
Testing 1243 by the primes up to its square root
| Prime | Division | Result |
|---|---|---|
| 2 | 1243 ÷ 2 | leaves 1 |
| 3 | 1243 ÷ 3 | leaves 1 |
| 5 | 1243 ÷ 5 | leaves 3 |
| 7 | 1243 ÷ 7 | leaves 4 |
| 11 | 1243 ÷ 11 | divides exactly (113) |
| 13 | 1243 ÷ 13 | leaves 8 |
| 17 | 1243 ÷ 17 | leaves 2 |
| 19 | 1243 ÷ 19 | leaves 8 |
| 23 | 1243 ÷ 23 | leaves 1 |
| 29 | 1243 ÷ 29 | leaves 25 |
| 31 | 1243 ÷ 31 | leaves 3 |
Questions
Is 1243 a prime number?
No, 1243 is not a prime number. It is divisible by 11: 1243 = 11 × 113.
What is the next prime after 1243?
1249.
What is the prime number before 1243?
1237.
What are the factors of 1243?
1, 11, 113, 1243.