Is 61 a prime number?
61 is a prime number. Here is how to check it, one division at a time.
The answer
Yes. 61 is a prime number: its only factors are 1 and 61.
How to check that 61 is prime
Try dividing 61 by the prime numbers, starting with 2. You only need primes: if 4 went into 61, then 2 would too.
- 61 ÷ 2 = 30 remainder 1, so 2 is not a factor.
- 61 ÷ 3 = 20 remainder 1, so 3 is not a factor.
- 61 ÷ 5 = 12 remainder 1, so 5 is not a factor.
- 61 ÷ 7 = 8 remainder 5, so 7 is not a factor.
Stop at 11: 11 × 11 = 121, which is more than 61. Any factor bigger than that would need a partner smaller than 11, and you have already tried those. So 61 is prime.
Where 61 comes among the primes
61 is the 18th prime number. The prime just before it is 59.
There are 25 prime numbers up to 100: 2, 3, 5, 7, 11, 13, 17, 19, 23, 29, 31, 37, 41, 43, 47, 53, 59, 61, 67, 71, 73, 79, 83, 89 and 97.
Around 61
- 61 is not in any times table from 2 to 12. The answers either side of it are 60 (5 × 12, 6 × 10, 10 × 6 and 12 × 5) and 63 (7 × 9 and 9 × 7).
- The nearest square number is 64 (8 × 8), 3 above it.
61 at a glance
Optional extra number facts:
- In words
- sixty-one
- In Roman numerals
- LXI
- Odd or even
- Odd: it ends in 1
- Its factors add up to
- 62, or 1 without 61 itself. 61 is deficient: Deficient means this sum is less than the number.
Related pages
More numbers
Questions parents ask
Is 61 one of a pair of twin primes?
Yes. Twin primes are two primes 2 apart, and 61 pairs with 59.
What is the next prime number after 61?
67, which is 6 more than 61. Every number in between has a factor other than 1 and itself.
What is 61 × 61?
61 × 61 = 3721. The square of a prime has exactly three factors: 1, 61 and 3721.
Continue your number practice
Explore the diagnostic for another set of practice questions.