Is 603 a prime number?
No. 603 is divisible by 3. 603 divided by 3 is actually 201, making 603 a composite number.(If the sum of all the digits in a number is divisible by 3, the number is divisible by 3. In this case, 6+0+3=9, and since 9 is divisible by 3 so is 603. )