The General Multiprecision PYthon project (GMPY) focuses on Python-usable modules providing multiprecision arithmetic functionality to Python programmers.
Some informational text and old download files are at https://gmpy.sourceforge.net/
The project has now moved to google-code: https://code.google.com/p/gmpy
...which has been moved to GitHub: https://github.com/aleaxit/gmpy
GNU Multiple Precision Arithmetic Library https://gmplib.org