Is 70 a prime number?
70 is not a prime number. Here is the quickest way to see it.
The answer
No. 70 is not a prime number: 2 × 35 = 70.
How to see that 70 is not prime
70 is even, and every even number can be divided by 2, so 2 is a factor as well as 1 and 70.
70 has 8 factors (1, 2, 5, 7, 10, 14, 35 and 70), which make 4 factor pairs.
Split 70 into prime factors
Split off the smallest prime each time, and keep going until every part is prime:
- 70 = 2 × 35
- 70 = 2 × 5 × 7
70 in the times tables
70 turns up in 2 different times tables, the 7 and 10: 7 × 10 and 10 × 7.
Quick checks that catch 70
- The last digit, 0, is even, so 2 goes in.
- It ends in 0, so 5 goes in.
- It ends in 0, so 10 goes in.
70 at a glance
- In words
- seventy
- In Roman numerals
- LXX
- Odd or even
- Even: it ends in 0
- Multiple of 10
- 7 tens
- Its factors add up to
- 144, or 74 without 70 itself, which makes 70 an abundant number
The numbers either side of 70
- 69 is not prime. Its digits add up to 6 + 9 = 15, which is a multiple of 3. That means 69 is a multiple of 3 too, so 3 is a factor. Check 69 in full
- 71 is prime: 2, 3, 5 and 7 do not go into it, and 11 × 11 is already past 71. Check 71 in full
Related pages
More numbers
Questions parents ask
Which prime numbers are either side of 70?
67 below it and 71 above it, a gap of 4.
What is 70 squared?
70 × 70 = 4900.
What is the smallest number with as many factors as 70?
24. It has 8 factors, the same as 70.
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.