Is 47 a prime number?
47 is a prime number. Here is how to check it, one division at a time.
The answer
Yes. 47 is a prime number: its only factors are 1 and 47.
How to check that 47 is prime
Try dividing 47 by the prime numbers, starting with 2. You only need primes: if 4 went into 47, then 2 would too.
- 47 ÷ 2 = 23 remainder 1, so 2 is not a factor.
- 47 ÷ 3 = 15 remainder 2, so 3 is not a factor.
- 47 ÷ 5 = 9 remainder 2, so 5 is not a factor.
Stop at 7: 7 × 7 = 49, which is more than 47. Any factor bigger than that would need a partner smaller than 7, and you have already tried those. So 47 is prime.
Where 47 comes among the primes
47 is the 15th prime number. The prime just before it is 43.
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 47
- 47 is not in any times table from 2 to 12. The answers either side of it are 45 (5 × 9 and 9 × 5) and 48 (4 × 12, 6 × 8, 8 × 6 and 12 × 4).
- The nearest square number is 49 (7 × 7), 2 above it.
- Two prime numbers with a difference of 4 are called cousin primes. 47 has one cousin prime: 43.
47 at a glance
Optional extra number facts:
- In words
- forty-seven
- In Roman numerals
- XLVII
- Odd or even
- Odd: it ends in 7
- Its factors add up to
- 48, or 1 without 47 itself. 47 is deficient: Deficient means this sum is less than the number.
Related pages
More numbers
Questions parents ask
Is 47 one of a pair of twin primes?
No. Twin primes are two primes 2 apart, such as 11 and 13. Neither 45 nor 49 is prime, so 47 has no twin.
What is the next prime number after 47?
53, which is 6 more than 47. Every number in between has a factor other than 1 and itself.
What is 47 × 47?
47 × 47 = 2209. The square of a prime has exactly three factors: 1, 47 and 2209.
Continue your number practice
Explore the diagnostic for another set of practice questions.