What is a amstrong number?

An Armstrong number, also known as a narcissistic number, is a number that is equal to the sum of its own digits each raised to the power of the number of digits. For example, 153 is an Armstrong number because it has three digits, and (1^3 + 5^3 + 3^3 = 153). Armstrong numbers can be found in various bases, though they are most commonly discussed in base 10. Examples include 0, 1, 2, 3, 4, 5, 6, 7, 8, 9, 153, 370, and 9474.