Is 7 a prime number?

Prime Number Checker

Is 7 a prime or composite number?

Answer

Number 7 is a Prime

7 has exactly two divisors — 1 and 7 — so it is a prime.

Primes up to √7

2² = 4 ≤ 7 < 9 = 3², so it is enough to try primes up to 2

2 does not divide 7 — 7 is prime

Nearest primes: 5 and 11

Number	Is Prime
1	No: neither prime nor composite
2	Yes
3	Yes
4	No: 2²
5	Yes
6	No: 2 × 3
7	Yes
8	No: 2³
9	No: 3²
10	No: 2 × 5
11	Yes
12	No: 2² × 3
13	Yes
14	No: 2 × 7
15	No: 3 × 5
16	No: 2⁴
17	Yes
18	No: 2 × 3²
19	Yes
20	No: 2² × 5
21	No: 3 × 7
22	No: 2 × 11
23	Yes
24	No: 2³ × 3
25	No: 5²
26	No: 2 × 13
27	No: 3³
28	No: 2² × 7
29	Yes
30	No: 2 × 3 × 5

Number 7 is a Prime

Divide 7 by the primes in order: 2² = 4 ≤ 7 < 9 = 3², so it is enough to try primes up to 2. None of the 1 primes up to 2 divides 7, so 7 is prime.