It is 23
The first prime number after 18 is 19.
19 is a prime.
19 is a prime number.19 is a prime number.19 is a prime number.19 is a prime number.
19 is a prime number, so it has no prime factorization.
19 is the prime number.
19 is a prime number.
19 is a prime number
19 is prime.
19 is a prime number.
1 and 19 (19 is a prime number).
Being a prime number, 19 only has 2 factors: 1 & 19.
19 is a prime number.