Factors of 45
There are 6 factors of 45 — the full list is below, with factor pairs, prime factorization, and divisibility notes.
Factors of 45
1, 3, 5, 9, 15, 45
Factor pairs of 45
- 1 × 45
- 3 × 15
- 5 × 9
Prime factorization of 45
45 = 3² × 5
Number facts
- 45 is a composite number.
- 45 has 6 factors.
- 45 is not a perfect square.
- The sum of all factors of 45 is 78.
Divisibility rules that apply to 45
- 45 is divisible by 3 because the sum of its digits (9) is divisible by 3.
- 45 is divisible by 5 because it ends in 0 or 5.
- 45 is divisible by 9 because the sum of its digits (9) is divisible by 9.
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How the factors of 45 are calculated
To find the factors of 45, every whole number from 1 up to the square root of 45(about 6.71) is tested for even division. 45 is odd, and it divides evenly by 3, 5, 9, 15. Written as a product of primes, 45 = 3² × 5, which confirms every factor above is a combination of those prime building blocks.
Frequently asked questions about 45
How many factors does 45 have?
45 has 6 factors: 1, 3, 5, 9, 15, 45.
Is 45 a prime number?
No. 45 is composite because it has factors other than 1 and itself.
What are the factor pairs of 45?
The factor pairs of 45 are 1 × 45, 3 × 15, 5 × 9.
What is the prime factorization of 45?
The prime factorization of 45 is 3² × 5.