Zero (0) is considered an even number. In mathematics, even numbers are defined as divisible by 2 without leaving a remainder. Since 0 divided by 2 equals 0, it meets the criteria of being an even number.

In number theory, even numbers have some unique properties. For example, any even number can be expressed as the sum of two equal integers. In the case of 0, it can be written as 0 + 0 or (-1) + 1, showing its even nature.

Furthermore, zero plays a significant role in mathematical operations. It is the additive identity, meaning that any number added to zero remains unchanged. This property is crucial in various mathematical concepts and calculations.

It is important to note that zero is neither positive nor negative. It is classified as neither odd nor even in some contexts. However, from a rigorous mathematical standpoint, it falls under the category of even numbers.