# 4 | | **4** (four) is a number, numeral and digit. It is the natural number following 3 and preceding 5. It is a square number, the smallest semiprime and composite number, and is considered unlucky in many East Asian cultures. | |-|-| | | wikipedia:: [4](https://en.wikipedia.org/wiki/4) | aka:: "tetrad" [[Number#Terms and words for numbers]]