Is 65 a prime number?
65 is not a prime number. Here is a way to check it.
The answer
No. 65 is not a prime number: 5 × 13 = 65.
How to see that 65 is not prime
65 ends in 5, and every number ending in 5 or 0 is in the 5 times table, so 5 is a factor.
65 has four factors: 1 and 65, plus one pair in between, 5 and 13.
Split 65 into prime factors
65 splits straight into two primes, 5 × 13, so its factor tree has only one branch.
65 in the times tables
No fact from the 2 to 12 times tables, up to × 12, makes 65. Its smallest pair, 5 × 13, needs the 13 times table, which goes past 12.
See the 13 times table, where 13 × 5 = 65 is one of the facts.
Quick checks that catch 65
- It ends in 5, so 5 goes in.
65 at a glance
Optional extra number facts:
- In words
- sixty-five
- In Roman numerals
- LXV
- Odd or even
- Odd: it ends in 5
- Its factors add up to
- 84, or 19 without 65 itself. 65 is deficient: Deficient means this sum is less than the number.
The numbers either side of 65
- 64 is not prime. 64 is even, and every even number can be divided by 2, so 2 is a factor as well as 1 and 64. Check 64 in full
- 66 is not prime. 66 is even, and every even number can be divided by 2, so 2 is a factor as well as 1 and 66. Check 66 in full
Turn the digits round
65 backwards is 56. 56 is not prime. 56 is even, and every even number can be divided by 2, so 2 is a factor as well as 1 and 56. Check 56 in full
Related pages
More numbers
Questions parents ask
Which prime numbers are either side of 65?
61 below it and 67 above it, a gap of 6.
What is 65 squared?
65 × 65 = 4225.
What is the smallest number with as many factors as 65?
6. It has 4 factors, the same as 65.
Continue your number practice
Explore the diagnostic for another set of practice questions.