A prime number is a positive integer with exactly two positive factors: \(1\) and itself. For example,
\(2\) is prime, as its positive factors are \(1\) and \(2\)
\(4\) is not prime, as its positive factors include \(2\)
\(1\) is not prime, as its only positive factor is \(1\)
\(0\) is not prime, as it is not a positive integer
Numbers which are not prime are called composite numbers.
Sometimes, the term prime number is used in a wider sense to include negative integers; a negative integer is prime if it is the negative of a (positive) prime number. Zero is neither prime nor composite.
