223 is a prime number. You can prove it by showing it is not divisible by 2, 3, 5, 7, 9, 11, 13, and 15 (2 and all the odd numbers up to the square root of 223)

8 is, because it's the only perfect cube. 39 is, because it's the only one divisible by 13. 51 is, because it's the only one divisible by 17. 123 is, because it's the only one divisible by 41. 124 is, because it's the only one divisible by 31 892 is, because it's the only one divisible by 223.