Is 64 a prime number?
64 is not a prime number. Here is the quickest way to see it.
The answer
No. 64 is not a prime number: 2 × 32 = 64.
How to see that 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.
64 has 7 factors (1, 2, 4, 8, 16, 32 and 64), which make 4 factor pairs.
Split 64 into prime factors
Split off the smallest prime each time, and keep going until every part is prime:
- 64 = 2 × 32
- 64 = 2 × 2 × 16
- 64 = 2 × 2 × 2 × 8
- 64 = 2 × 2 × 2 × 2 × 4
- 64 = 2 × 2 × 2 × 2 × 2 × 2
With the repeated primes written as powers, that is 2⁶.
64 in the times tables
Just one of the 2 to 12 times tables has 64 in it: 8 × 8 = 64.
Quick checks that catch 64
- The last digit, 4, is even, so 2 goes in.
- Half of it is 32, which is still even, so 4 goes in.
64 at a glance
- In words
- sixty-four
- In Roman numerals
- LXIV
- Odd or even
- Even: it ends in 4
- Square number
- 8 × 8 = 64
- Cube number
- 4 × 4 × 4 = 64
- Its factors add up to
- 127, or 63 without 64 itself, which makes 64 a deficient number
The numbers either side of 64
- 63 is not prime. Its digits add up to 6 + 3 = 9, which is a multiple of 3. That means 63 is a multiple of 3 too, so 3 is a factor. Check 63 in full
- 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. Check 65 in full
Turn the digits round
64 backwards is 46. 46 is not prime. 46 is even, and every even number can be divided by 2, so 2 is a factor as well as 1 and 46. Check 46 in full
Related pages
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Questions parents ask
Which prime numbers are either side of 64?
61 below it and 67 above it, a gap of 6.
What is 64 squared?
64 × 64 = 4096.
What is the smallest number with as many factors as 64?
64 itself. No smaller number has 7 factors.
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.