def sum_xor(n):
    # Time complexity: O(log(n))
    # Space complexity (ignoring input): O(1)
    if n == 0:
        return 1
    # count 0 in binary of number
    count = 0
    while n > 0:
        if n & 1 == 0:
            count += 1
        n = n >> 1

    return 2**count