Open the exe file with UltraEdit (or any other editor with binaries capabilities), and check if you have PE..L (32bit) or PE..d† (64bit).
But since Peopletools 8.5x are supported only on 64bit Windows server, who cares ?
Yes, it does need the Oracle 32bit client binaries on Windows. But installing a 32bit appl on a 64bit OS does not hurt, the other way cannot work.
Again, keep in mind the certification matrix (64bit OS only for PTools 8.5x - apps/batch/pia).