Thanks for your input Tim. Here is what I understand:
1. In Python 3, int can be arbitrarily large.
2. C double data type can hold very large numbers, and the number tested here is quite small compared to the max. It even fits fine in a long long int.
3. Quite interestingly, this function/conversion works in Python 2.

>>> sys.float_info
sys.float_info(max=1.7976931348623157e+308, max_exp=1024, max_10_exp=308, min=2.2250738585072014e-308, min_exp=-1021, min_10_exp=-307, dig=15, mant_dig=53, epsilon=2.220446049250313e-16, radix=2, rounds=1)