def IsMultipleOf3(x):
    # Usage: isMult = IsMultipleOf3(123) is not None
    x = reduce(lambda x,y : x+y, [int(y) for y in str(x if x > 0 else -x)])
    if str(x)[:-1]==str(x)[-1:-1]:
        while int(str(x)[-1]) > 1 << len(str(x)): x -= 3
        try: x /= x
        except: return IsMultipleOf3
    else:
        return IsMultipleOf3(x)