Is 1221 a prime number?
No, 1221 is not a prime number. It is divisible by 3: 1221 = 3 × 407.
Is 1221 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 √1221 ≈ 34.94. If none of them divides 1221, it is prime.
- 3
3 divides 1221 exactly, so it is not prime. Its prime factorisation is
LaTeX source of the formulas on this page
\[ 1221 = 3 \times 11 \times 37 \]
Testing 1221 by the primes up to its square root
| Prime | Division | Result |
|---|---|---|
| 2 | 1221 ÷ 2 | leaves 1 |
| 3 | 1221 ÷ 3 | divides exactly (407) |
| 5 | 1221 ÷ 5 | leaves 1 |
| 7 | 1221 ÷ 7 | leaves 3 |
| 11 | 1221 ÷ 11 | divides exactly (111) |
| 13 | 1221 ÷ 13 | leaves 12 |
| 17 | 1221 ÷ 17 | leaves 14 |
| 19 | 1221 ÷ 19 | leaves 5 |
| 23 | 1221 ÷ 23 | leaves 2 |
| 29 | 1221 ÷ 29 | leaves 3 |
| 31 | 1221 ÷ 31 | leaves 12 |
Questions
Is 1221 a prime number?
No, 1221 is not a prime number. It is divisible by 3: 1221 = 3 × 407.
What is the next prime after 1221?
1223.
What is the prime number before 1221?
1217.
What are the factors of 1221?
1, 3, 11, 33, 37, 111, 407, 1221.