Which number is the only even prime number?

The only even prime number is two because it is the only number that is both even and meets the definition of a prime number. A prime number is defined as a natural number greater than one that has no positive divisors other than one and itself.

Two fits this definition perfectly: its only divisors are one and two, making it prime. All other even numbers greater than two can be divided by two, meaning they have at least three divisors (one, two, and the number itself), which disqualifies them from being prime.

In contrast, one is not considered a prime number by definition, as it does not exceed one. Three and five are odd prime numbers but do not meet the criteria for evenness. Thus, the uniqueness of two as the only even prime number is clear.