Factors of 57
The factors of 57 are 1, 3, 19, 57. No, 57 is a composite number. Its prime factorization is 3 × 19.
Factor pairs of 57
Every factor has a partner that multiplies with it to give 57. Listing pairs from the outside in is the fastest way to find all the factors: once the two numbers in a pair meet in the middle, you have them all.
| Pair | Check |
|---|---|
| 1 and 57 | 1 × 57 = 57 |
| 3 and 19 | 3 × 19 = 57 |
Prime factorization of 57, step by step
Divide by the smallest prime that goes in evenly, then repeat on the result until you reach 1. The divisors you used are the prime factors.
| Step | Divide | Result |
|---|---|---|
| 1 | 57 ÷ 3 | 19 |
| 2 | 19 ÷ 19 | 1 |
So 57 = 3 × 19, written compactly as 3 × 19.
Divisibility checks for 57
The quick rules a student uses before dividing, applied to 57:
| Divisible by | Rule | For 57 | Result |
|---|---|---|---|
| 2 | last digit is even | last digit 7 | no |
| 3 | digit sum divisible by 3 | digits add to 12 | yes |
| 4 | last two digits divisible by 4 | 57 ÷ 4 | no |
| 5 | last digit is 0 or 5 | last digit 7 | no |
| 6 | divisible by both 2 and 3 | odd, digit sum 12 | no |
| 8 | last three digits divisible by 8 | 57 ÷ 8 | no |
| 9 | digit sum divisible by 9 | digits add to 12 | no |
| 10 | last digit is 0 | last digit 7 | no |
Frequently Asked Questions
What are the factors of 57?
The factors of 57 are 1, 3, 19, 57.
Is 57 a prime number?
No, 57 is a composite number. Its prime factorization is 3 × 19.
How many factors does 57 have?
57 has 4 factors. You can get that count from the prime factorization without listing them: add 1 to each exponent in 3 × 19 and multiply -- (1+1) × (1+1) = 4.
Is 57 even or odd?
57 is odd (2 is not a factor).
What is the sum of the factors of 57?
1 + 3 + 19 + 57 = 80. Leaving out 57 itself, the proper factors add to 23, less than 57, so 57 is a deficient number.
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