A number (other than 1) which is not a prime number is called a composite number.
If a prime of the second form gets into your composite number, then that number cannot be the sum of two squares.
|composite number |
An integer that can be divided by at least one other integer besides itself and 1 without leaving a remainder. 24 is a composite number since it can be divided by 2, 3, 4, 6, 8, and 12. No prime numbers are composite numbers. Compare prime number.