Which of the following is an Armstrong number?(Armstrong number is a number that is equal to the sum of cubes of its digits.) 123 333 407 663

To find out which of the given numbers is an Armstrong number, we need to check each number individually.

1. 123: The cube of each digit is 1^3=1, 2^3=8, 3^3=27. The sum of these is 1+8+27=36, which is not equal to 123. So, 123 is not an Armstrong number.

2. 333: The cube of each digit is 3^3=27. The sum of these is 27+27+27=81, which is not equal to 333. So, 333 is not an Armstrong number.

3. 407: The cube of each digit is 4^3=64, 0^3=0, 7^3=343. The sum of these is 64+0+343=407, which is equal to 407. So, 407 is an Armstrong number.

4. 663: The cube of each digit is 6^3=216, 6^3=216, 3^3=27. The sum of these is 216+216+27=459, which is not equal to 663. So, 663 is not an Armstrong number.

Therefore, the only Armstrong number in the list is 407.