Dear rapecchik, I really admire that you have asked such an important question here. Most of the Outlook users don't even know that which Outlook version are they using, i.e. either they are using 32-bit or 64-bit.
Here is a simple way to find out either you are using MS Outlook 32-bit or 64-bit:1.
Launch MS Outlook
on your system.2.
Now click File
tab > Help
Check at the right hand side.
Your MS Outlook version is shown here.
Hope this would be enough for you.