Factors of 39
The factors of 39 are 1, 3, 13, 39. 39 is a composite number with 4 factors. Prime factorisation: 3 × 13.
All 4 factors of 39
1, 3, 13, 39
A factor divides 39 exactly, with no remainder. Every factor has a partner: the pairs below multiply to 39. The negative factors are -1, -3, -13, -39, because a negative times a negative is positive.
Factor pairs of 39
| Pair | Product |
|---|---|
| 1 × 39 | 39 |
| 3 × 13 | 39 |
Stop at the square root (6): every pair after that is one you already have, the other way round.
Prime factorisation of 39: 3 × 13
| Divide | by the smallest prime | Result |
|---|---|---|
| 39 | 3 | 13 |
| 13 | 13 | 1 |
So 39 = 3 × 13.
The number of factors comes from the exponents: (1 + 1) × (1 + 1) = 4.
How to find the factors of 39
- Start with 1 and 39: every number has those two.
- Test 2, 3, 4, … up to the square root of 39, which is about 6.
- Each time a number divides exactly, write it down with its partner (the quotient).
- Use the divisibility rules to skip work: by 2 no (the last digit is odd); by 3 yes (the digit sum is 12); by 5 no (the last digit is 9).
- Put the list in order: 1, 3, 13, 39.
🧮 Calculator
The answer appears here, with the working in words.
✏️ Five questions, answers hidden
1. List the factors of 40.
Answer: 1, 2, 4, 5, 8, 10, 20, 40
2. Write the prime factorisation of 78.
Answer: 2 × 3 × 13
3. How many factors does 39 have?
Answer: 4
4. What is the largest factor of 39 other than itself?
Answer: 13
5. Is 41 prime or composite?
Answer: prime
📚 The class this belongs to
Factors are taught in Grade 4 and 5 in the US, Year 5 and 6 in the UK, Class 4 to 6 in CBSE (NCERT Class 6, Playing with Numbers) and Year 5 and 6 in Australia.
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