Two is the only even prime number because other even numbers have at least three or more positive divisors. A number can only be considered prime when it only has two positive divisors: itself and 1.
Even numbers that are higher than 2 are composite numbers, because they have already themselves, 2 and 1 as definite divisors. There is an infinite number of primes, all of which (except the number 2) are odd numbers. A simple way to determine the primality of a number is through trial division, which is done by dividing the number starting with the divisor 2 and up to the number's square root. If any of the quotients doesn't have a remainder, then the number is not a prime number.