In [20]:
"""
2^15 = 32768 and the sum of its digits is 3 + 2 + 7 + 6 + 8 = 26.

What is the sum of the digits of the number 2^1000?
"""

def sum_digits(n):
    """Returns sum of digits in n."""
    return sum(map(int, str(n)))

In [21]:
sum_digits(2**1000)


Out[21]:
1366