Is 221 a prime number?
No, 221 is not a prime number. It is divisible by 13: 221 = 13 × 17.
Is 221 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 √221 ≈ 14.87. If none of them divides 221, it is prime.
- 3
13 divides 221 exactly, so it is not prime. Its prime factorisation is
LaTeX source of the formulas on this page
\[ 221 = 13 \times 17 \]
Testing 221 by the primes up to its square root
| Prime | Division | Result |
|---|---|---|
| 2 | 221 ÷ 2 | leaves 1 |
| 3 | 221 ÷ 3 | leaves 2 |
| 5 | 221 ÷ 5 | leaves 1 |
| 7 | 221 ÷ 7 | leaves 4 |
| 11 | 221 ÷ 11 | leaves 1 |
| 13 | 221 ÷ 13 | divides exactly (17) |
Questions
Is 221 a prime number?
No, 221 is not a prime number. It is divisible by 13: 221 = 13 × 17.
What is the next prime after 221?
223.
What is the prime number before 221?
211.
What are the factors of 221?
1, 13, 17, 221.