Is 9991 a prime number?
No, 9991 is not a prime number. It is divisible by 97: 9991 = 97 × 103.
Is 9991 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 √9991 ≈ 99.95. If none of them divides 9991, it is prime.
- 3
97 divides 9991 exactly, so it is not prime. Its prime factorisation is
LaTeX source of the formulas on this page
\[ 9991 = 97 \times 103 \]
Testing 9991 by the primes up to its square root
| Prime | Division | Result |
|---|---|---|
| 2 | 9991 ÷ 2 | leaves 1 |
| 3 | 9991 ÷ 3 | leaves 1 |
| 5 | 9991 ÷ 5 | leaves 1 |
| 7 | 9991 ÷ 7 | leaves 2 |
| 11 | 9991 ÷ 11 | leaves 3 |
| 13 | 9991 ÷ 13 | leaves 7 |
| 17 | 9991 ÷ 17 | leaves 12 |
| 19 | 9991 ÷ 19 | leaves 16 |
| 23 | 9991 ÷ 23 | leaves 9 |
| 29 | 9991 ÷ 29 | leaves 15 |
| 31 | 9991 ÷ 31 | leaves 9 |
| 37 | 9991 ÷ 37 | leaves 1 |
Questions
Is 9991 a prime number?
No, 9991 is not a prime number. It is divisible by 97: 9991 = 97 × 103.
What is the next prime after 9991?
10007.
What is the prime number before 9991?
9973.
What are the factors of 9991?
1, 97, 103, 9991.