Is 31 a prime number?

Prime Number Checker
Number

Is 31 a prime or composite number?

Answer

Number 31 is a Prime

31 has exactly two divisors — 1 and 31 — so it is a prime.

Primes up to √31

5² = 25 ≤ 31 < 36 = 6², so it is enough to try primes up to 5

  • ÷2 does not divide
  • ÷3 does not divide
  • ÷5 does not divide

none of the 3 primes up to 5 divides 31 — 31 is prime

Nearest primes: 29 and 37

Related Calculations

See Also

Prime numbers list

NumberIs Prime
16No: 2⁴
17Yes
18No: 2 × 3²
19Yes
20No: 2² × 5
21No: 3 × 7
22No: 2 × 11
23Yes
24No: 2³ × 3
25No: 5²
26No: 2 × 13
27No: 3³
28No: 2² × 7
29Yes
30No: 2 × 3 × 5
31Yes
32No: 2⁵
33No: 3 × 11
34No: 2 × 17
35No: 5 × 7
36No: 2² × 3²
37Yes
38No: 2 × 19
39No: 3 × 13
40No: 2³ × 5
41Yes
42No: 2 × 3 × 7
43Yes
44No: 2² × 11
45No: 3² × 5

FAQ

Is 31 a prime or composite number?

Number 31 is a Prime

How many factors are in a number 31?

2

How to check if 31 is prime?

Divide 31 by the primes in order: 5² = 25 ≤ 31 < 36 = 6², so it is enough to try primes up to 5. None of the 3 primes up to 5 divides 31, so 31 is prime.

See Also