Is 33 a prime number?
33 is not a prime number. Here is the quickest way to see it.
The answer
No. 33 is not a prime number: 3 × 11 = 33.
How to see that 33 is not prime
Its digits add up to 3 + 3 = 6, which is a multiple of 3. That means 33 is a multiple of 3 too, so 3 is a factor.
33 has four factors: 1 and 33, plus one pair in between, 3 and 11.
Split 33 into prime factors
33 splits straight into two primes, 3 × 11, so its factor tree has only one branch.
33 in the times tables
33 turns up in 2 different times tables, the 3 and 11: 3 × 11 and 11 × 3.
Quick checks that catch 33
- The digits add up to 6, which is in the 3 times table, so 3 goes in.
- Its two digits match, and every two-digit number like that is in the 11 times table.
33 at a glance
- In words
- thirty-three
- In Roman numerals
- XXXIII
- Odd or even
- Odd: it ends in 3
- Its factors add up to
- 48, or 15 without 33 itself, which makes 33 a deficient number
The numbers either side of 33
- 32 is not prime. 32 is even, and every even number can be divided by 2, so 2 is a factor as well as 1 and 32. Check 32 in full
- 34 is not prime. 34 is even, and every even number can be divided by 2, so 2 is a factor as well as 1 and 34. Check 34 in full
Related pages
More numbers
Questions parents ask
Which prime numbers are either side of 33?
31 below it and 37 above it, a gap of 6.
What is 33 squared?
33 × 33 = 1089.
What is the smallest number with as many factors as 33?
6. It has 4 factors, the same as 33.
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.