Factors of 21
21 has 4 factors.
All factors of 21
1, 3, 7, 21
Prime factorization: 3 × 7
Number of factors
4
Sum of factors
32
Prime?
No
Factor pairs of 21
Each pair multiplies together to make 21:
| Pair | Product |
|---|---|
| 1 × 21 | 21 |
| 3 × 7 | 21 |
Factors of nearby numbers
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Frequently asked questions
What are the factors of 21?+
The factors of 21 are 1, 3, 7, 21 — that is 4 factors in total.
What is the prime factorization of 21?+
The prime factorization of 21 is 3 × 7.
Is 21 a prime number?+
No. 21 has 4 factors, more than just 1 and itself, so it is a composite number.