Is 89 a prime number?
89 is a prime number. Here is how to check it, one division at a time.
The answer
Yes. 89 is a prime number: its only factors are 1 and 89.
How to check that 89 is prime
Try dividing 89 by the prime numbers, starting with 2. You only need primes: if 4 went into 89, then 2 would too.
- 89 ÷ 2 = 44 remainder 1, so 2 is not a factor.
- 89 ÷ 3 = 29 remainder 2, so 3 is not a factor.
- 89 ÷ 5 = 17 remainder 4, so 5 is not a factor.
- 89 ÷ 7 = 12 remainder 5, so 7 is not a factor.
Stop at 11: 11 × 11 = 121, which is more than 89. Any factor bigger than that would need a partner smaller than 11, and you have already tried those. So 89 is prime.
Where 89 comes among the primes
89 is the 24th prime number. The prime just before it is 83.
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 89
- 89 is not in any times table from 2 to 12. The answers either side of it are 88 (8 × 11 and 11 × 8) and 90 (9 × 10 and 10 × 9).
- The nearest square number is 81 (9 × 9), 8 below it.
89 at a glance
- In words
- eighty-nine
- In Roman numerals
- LXXXIX
- Odd or even
- Odd: it ends in 9
- Its factors add up to
- 90, or 1 without 89 itself, which makes 89 a deficient number
Related pages
More numbers
Questions parents ask
Is 89 one of a pair of twin primes?
No. Twin primes are two primes 2 apart, such as 11 and 13. Neither 87 nor 91 is prime, so 89 has no twin.
What is the next prime number after 89?
97, which is 8 more than 89. Every number in between has a factor other than 1 and itself.
What is 89 × 89?
89 × 89 = 7921. The square of a prime has exactly three factors: 1, 89 and 7921.
Number facts are the base of 11+ maths
Factors, multiples, primes and square numbers come up all over 11+ maths, from simplifying fractions to ratio. The free diagnostic checks maths, English and both kinds of reasoning, and shows what to practise next. No card is required.