where is python installed windows

1>>> import os
2>>> import sys
3>>> os.path.dirname(sys.executable)
4'C:\\Python25'

1pip list -v  # Or pip3 list -v 
2
3# output example (windows 10):
4# Package                   Version   Location                                                         Installer
5# ------------------------- --------- ---------------------------------------------------------------- ---------
6# adal                      0.4.5     c:\users\test\appdata\roaming\python\python36\site-packages      pip
7# aiocache                  0.10.0    c:\program files\python36\lib\site-packages

1You cannot just pip install python3 because it is not a library.
2
3If you want to install the latest python3:
4https://www.python.org/ftp/python/3.8.2/python-3.8.2.exe 

11. Open start menu and type python
22. Right click on python and select open file location. It will a window in explorer just like below.
33. Again , right click on selected python and select open file location. A window will open and you are now in python’s installation directory.

1Python usually stores its library (and thereby your site-packages folder) 
2in the installation directory. So, if you had installed Python to 
3C:\Python\, the default library would reside in C:\Python\Lib\ 
4and third-party modules should be stored in C:\Python\Lib\site-packages.