Factors of 91
Every whole number that divides 91 exactly, the factor pairs, and how to find them yourself.
The answer
The factors of 91 are 1, 7, 13 and 91.
Factor pairs of 91
| Pair | Makes |
|---|---|
| 1 × 91 | 91 |
| 7 × 13 | 91 |
Prime factors of 91
- Prime factorisation
- 91 = 7 × 13
- Is 91 prime?
- No. It has 4 factors, not just 1 and 91.
- Is 91 a square number?
- No. 9 × 9 = 81 and 10 × 10 = 100, so 91 falls between two square numbers.
How to find the factors of 91
91 is odd, so every even number you try will fail. Work up from 1 to 9, and write down both numbers in every pair you find.
- 91 ÷ 1 = 91, so 1 × 91 is a pair.
- 2 does not go into 91 exactly.
- 3 does not go into 91 exactly.
- 4 does not go into 91 exactly.
- 5 does not go into 91 exactly.
- 6 does not go into 91 exactly.
- 91 ÷ 7 = 13, so 7 × 13 is a pair.
- 8 does not go into 91 exactly.
- 9 does not go into 91 exactly.
Stop at 10: 10 × 10 = 100, which is more than 91. The next pair you would find is 13 × 7, which is 7 × 13 turned round, so you already have every pair.
91 in the times tables
7 × 13 = 91. Practise the 13 times table.
More numbers
Check whether 91 is prime.
Questions parents ask
What is the largest factor of 91, apart from 91 itself?
13. Divide 91 by its smallest factor above 1, which is 7: 91 ÷ 7 = 13.
What do the factors of 91 add up to?
112. Leaving out 91 itself, they add up to 21, which is less than 91, so 91 is called a deficient number.
Which number after 91 has the same number of factors?
93. Like 91, it has exactly 4 factors.
Continue your number practice
Explore the diagnostic for another set of practice questions.