Project Euler: #16 - Power digit sum

Problem 215 = 32768 and the sum of its digits is 3 + 2 + 7 + 6 + 8 = 26. What is the sum of the digits of the number 21000? Problem Description The problem is pretty self-explanatory. 215 is 32768 and the sum of its digits is 3 + 2 + 7 + 6 + 8 = 26....