Skip to main content

Is 54 a prime number?

54 is not a prime number. Here is a way to check it.

The answer

No. 54 is not a prime number: 2 × 27 = 54.

How to see that 54 is not prime

54 is even, and every even number can be divided by 2, so 2 is a factor as well as 1 and 54.

54 has 8 factors (1, 2, 3, 6, 9, 18, 27 and 54), which make 4 factor pairs.

Split 54 into prime factors

Split off the smallest prime each time, and keep going until every part is prime:

  1. 54 = 2 × 27
  2. 54 = 2 × 3 × 9
  3. 54 = 2 × 3 × 3 × 3

With repeated primes written as powers, that is 2 × 3³. A small raised number tells you how many times to use that factor: for example, 2³ means 2 × 2 × 2.

54 in the times tables

54 turns up in 2 different times tables, the 6 and 9: 6 × 9 and 9 × 6.

Quick checks that catch 54

  • The last digit, 4, is even, so 2 goes in.
  • The digits add up to 9, which is in the 3 times table, so 3 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.

54 at a glance

Optional extra number facts:

In words
fifty-four
In Roman numerals
LIV
Odd or even
Even: it ends in 4
Its factors add up to
120, or 66 without 54 itself. 54 is abundant: Abundant means this sum is greater than the number.

The numbers either side of 54

  • 53 is prime: 2, 3, 5 and 7 do not go into it, and 11 × 11 is already past 53. Check 53 in full
  • 55 is not prime. 55 ends in 5, and every number ending in 5 or 0 is in the 5 times table, so 5 is a factor. Check 55 in full

Turn the digits round

54 backwards is 45. 45 is not prime. Its digits add up to 4 + 5 = 9, which is a multiple of 3. That means 45 is a multiple of 3 too, so 3 is a factor. Check 45 in full

Related pages

More numbers

Questions parents ask

Which prime numbers are either side of 54?

53 below it and 59 above it, a gap of 6.

What is 54 squared?

54 × 54 = 2916.

What is the smallest number with as many factors as 54?

24. It has 8 factors, the same as 54.

Continue your number practice

Explore the diagnostic for another set of practice questions.

Start free diagnostic