Is 243 a prime number?
No, 243 is not a prime number. It is divisible by 3: 243 = 3 × 81.
Is 243 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 √243 ≈ 15.59. If none of them divides 243, it is prime.
- 3
3 divides 243 exactly, so it is not prime. Its prime factorisation is
LaTeX source of the formulas on this page
\[ 243 = 3^{5} \]Testing 243 by the primes up to its square root
| Prime | Division | Result |
|---|---|---|
| 2 | 243 ÷ 2 | leaves 1 |
| 3 | 243 ÷ 3 | divides exactly (81) |
| 5 | 243 ÷ 5 | leaves 3 |
| 7 | 243 ÷ 7 | leaves 5 |
| 11 | 243 ÷ 11 | leaves 1 |
| 13 | 243 ÷ 13 | leaves 9 |
Questions
Is 243 a prime number?
No, 243 is not a prime number. It is divisible by 3: 243 = 3 × 81.
What is the next prime after 243?
251.
What is the prime number before 243?
241.
What are the factors of 243?
1, 3, 9, 27, 81, 243.