Is 22 a prime number?
22 is not a prime number. Here is the quickest way to see it.
The answer
No. 22 is not a prime number: 2 × 11 = 22.
How to see that 22 is not prime
22 is even, and every even number can be divided by 2, so 2 is a factor as well as 1 and 22.
22 has four factors: 1 and 22, plus one pair in between, 2 and 11.
Split 22 into prime factors
22 splits straight into two primes, 2 × 11, so its factor tree has only one branch.
22 in the times tables
22 turns up in 2 different times tables, the 2 and 11: 2 × 11 and 11 × 2.
Quick checks that catch 22
- The last digit, 2, is even, so 2 goes in.
- Its two digits match, and every two-digit number like that is in the 11 times table.
22 at a glance
- In words
- twenty-two
- In Roman numerals
- XXII
- Odd or even
- Even: it ends in 2
- Its factors add up to
- 36, or 14 without 22 itself, which makes 22 a deficient number
The numbers either side of 22
- 21 is not prime. Its digits add up to 2 + 1 = 3, which is a multiple of 3. That means 21 is a multiple of 3 too, so 3 is a factor. Check 21 in full
- 23 is prime: 2 and 3 do not go into it, and 5 × 5 is already past 23. Check 23 in full
Related pages
More numbers
Questions parents ask
Which prime numbers are either side of 22?
19 below it and 23 above it, a gap of 4.
What is 22 squared?
22 × 22 = 484.
What is the smallest number with as many factors as 22?
6. It has 4 factors, the same as 22.
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.