Is 84 a prime number?

• The last digit, 4, is even, so 2 goes in.
• The digits add up to 12, which is in the 3 times table, so 3 goes in.
• Half of it is 42, which is still even, so 4 goes in.
• It is even and passes the check for 3 as well, so 6 goes in.

Optional extra number facts:

In words

eighty-four

In Roman numerals

LXXXIV

Odd or even

Even: it ends in 4

Its factors add up to

224, or 140 without 84 itself. 84 is abundant: Abundant means this sum is greater than the number.

• 83 is prime: 2, 3, 5 and 7 do not go into it, and 11 × 11 is already past 83. Check 83 in full
• 85 is not prime. 85 ends in 5, and every number ending in 5 or 0 is in the 5 times table, so 5 is a factor. Check 85 in full

84 backwards is 48. 48 is not prime. 48 is even, and every even number can be divided by 2, so 2 is a factor as well as 1 and 48. Check 48 in full

• Every factor of 84, with the factor pairs
• 84 is a multiple of 2: see the multiples of 2