Is 49 a prime number?
49 is not a prime number. Here is a way to check it.
The answer
No. 49 is not a prime number: 7 × 7 = 49.
How to see that 49 is not prime
49 is odd, its digits do not add up to a multiple of 3, and it does not end in 5, so the quick checks for 2, 3 and 5 all fail. Try 7 next: 7 × 7 = 49.
Up to 100, the only composite numbers that pass the checks for 2, 3 and 5 are 49, 77 and 91, and 7 goes into all three.
49 has only three factors, 1, 7 and 49: just one more than a prime has, which is still enough to rule it out.
Why 49 looks prime
49 is 7 × 7, a square number. The square of a prime has exactly three factors, so 49 has only 1, 7 and 49: one factor too many to be prime. The next number like it is 121, which is 11 × 11.
Compare 47, the prime just below it. Try the same checks: 47 ÷ 2 = 23 remainder 1, 47 ÷ 3 = 15 remainder 2 and 47 ÷ 5 = 9 remainder 2. None goes in exactly, and 7 × 7 = 49 is more than 47, so 47 really is prime.
Split 49 into prime factors
49 is 7 × 7: the same prime twice, so its factor tree stops after one split.
49 in the times tables
Just one of the 2 to 12 times tables has 49 in it: 7 × 7 = 49.
Quick checks that catch 49
None of the digit checks work on 49: it is odd, its digit total is not a multiple of 3, and it does not end in 5 or 0. Dividing by 7 is one way to find a factor.
49 at a glance
Optional extra number facts:
- In words
- forty-nine
- In Roman numerals
- XLIX
- Odd or even
- Odd: it ends in 9
- Square number
- 7 × 7 = 49
- Its factors add up to
- 57, or 8 without 49 itself. 49 is deficient: Deficient means this sum is less than the number.
The numbers either side of 49
- 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
- 50 is not prime. 50 is even, and every even number can be divided by 2, so 2 is a factor as well as 1 and 50. Check 50 in full
Turn the digits round
49 backwards is 94. 94 is not prime. 94 is even, and every even number can be divided by 2, so 2 is a factor as well as 1 and 94. Check 94 in full
Related pages
More numbers
Questions parents ask
Which prime numbers are either side of 49?
47 below it and 53 above it, a gap of 6.
What is 49 squared?
49 × 49 = 2401.
What is the smallest number with as many factors as 49?
4. It has 3 factors, the same as 49.
Continue your number practice
Explore the diagnostic for another set of practice questions.