Composite number, a mathematical term, is called composite number in English, which refers to the number in natural numbers that can be divisible by other numbers (excluding 0) except 1 and itself. In contrast, it is a prime number (the factors are only 1 and itself, such as 2, 3, 5, 7, 1 1, 13, etc. And 1 is neither a prime number nor a composite number. The smallest composite number is 4.