Factors of 171
The factors of 171 are 1, 3, 9, 19, 57, 171. 171 is a composite number with 6 factors. Prime factorisation: 3^2 × 19.
All 6 factors of 171
1, 3, 9, 19, 57, 171
A factor divides 171 exactly, with no remainder. Every factor has a partner: the pairs below multiply to 171. The negative factors are -1, -3, -9, -19, -57, -171, because a negative times a negative is positive.
Factor pairs of 171
| Pair | Product |
|---|---|
| 1 × 171 | 171 |
| 3 × 57 | 171 |
| 9 × 19 | 171 |
Stop at the square root (13): every pair after that is one you already have, the other way round.
Prime factorisation of 171: 3^2 × 19
| Divide | by the smallest prime | Result |
|---|---|---|
| 171 | 3 | 57 |
| 57 | 3 | 19 |
| 19 | 19 | 1 |
So 171 = 32 × 19, that is 3 × 3 × 19.
The number of factors comes from the exponents: (2 + 1) × (1 + 1) = 6.
How to find the factors of 171
- Start with 1 and 171: every number has those two.
- Test 2, 3, 4, … up to the square root of 171, which is about 13.
- 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 9); by 5 no (the last digit is 1).
- Put the list in order: 1, 3, 9, 19, 57, 171.
🧮 Calculator
The answer appears here, with the working in words.
✏️ Five questions, answers hidden
1. List the factors of 172.
Answer: 1, 2, 4, 43, 86, 172
2. Write the prime factorisation of 342.
Answer: 2 × 3^2 × 19
3. How many factors does 171 have?
Answer: 6
4. What is the largest factor of 171 other than itself?
Answer: 57
5. Is 173 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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