Is 36 a prime number?
36 is not a prime number. Here is the quickest way to see it.
The answer
No. 36 is not a prime number: 2 × 18 = 36.
How to see that 36 is not prime
36 is even, and every even number can be divided by 2, so 2 is a factor as well as 1 and 36.
36 has 9 factors (1, 2, 3, 4, 6, 9, 12, 18 and 36), which make 5 factor pairs.
Split 36 into prime factors
Split off the smallest prime each time, and keep going until every part is prime:
- 36 = 2 × 18
- 36 = 2 × 2 × 9
- 36 = 2 × 2 × 3 × 3
With the repeated primes written as powers, that is 2² × 3².
36 in the times tables
36 turns up in 5 different times tables, the 3, 4, 6, 9 and 12: 3 × 12, 4 × 9, 6 × 6, 9 × 4 and 12 × 3.
Quick checks that catch 36
- The last digit, 6, is even, so 2 goes in.
- The digits add up to 9, which is in the 3 times table, so 3 goes in.
- Half of it is 18, which is still even, so 4 goes in.
- It is even and passes the check for 3 as well, so 6 goes in.
- The digit total, 9, is a multiple of 9, so 9 goes in.
36 at a glance
- In words
- thirty-six
- In Roman numerals
- XXXVI
- Odd or even
- Even: it ends in 6
- Square number
- 6 × 6 = 36
- Triangular number
- 1 + 2 + … + 8 = 36, a triangle of counters with 8 on the bottom row
- Its factors add up to
- 91, or 55 without 36 itself, which makes 36 an abundant number
The numbers either side of 36
- 35 is not prime. 35 ends in 5, and every number ending in 5 or 0 is in the 5 times table, so 5 is a factor. Check 35 in full
- 37 is prime: 2, 3 and 5 do not go into it, and 7 × 7 is already past 37. Check 37 in full
Turn the digits round
36 backwards is 63. 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
Related pages
More numbers
Questions parents ask
Which prime numbers are either side of 36?
31 below it and 37 above it, a gap of 6.
What is 36 squared?
36 × 36 = 1296.
What is the smallest number with as many factors as 36?
36 itself. No smaller number has 9 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.