Is 20 a prime number?

No, 20 is not a prime number. It is a composite number: it is even, so it is divisible by 2.

Why 20 is not prime

20 has divisors other than 1 and itself. The smallest is 2: 20 ÷ 2 = 10.

Prime factorization: 20 = 2 × 2 × 5 = 2² × 5.

Quick facts about 20

Even or odd: even.
Nearest primes: 19 below and 23 above.
Primes up to 20: 8.

Is it prime? Nearby numbers

Number	Prime?
16	No, 2 × 2 × 2 × 2
17	Yes
18	No, 2 × 3 × 3
19	Yes
21	No, 3 × 7
22	No, 2 × 11
23	Yes
24	No, 2 × 2 × 2 × 3

More about 20: factors of 20 · 20 squared · square root of 20 · 20 in binary · 20 in Roman numerals.

Another number? Use the prime number checker for any value, or see the list of prime numbers.