The latest version of Raspberry Pi comes with 64 bit CPU, but prior to that it was with 32 bit CPU. Some softwares and applications are dependent on CPU and OS architecture.
There are various options to check the architecture.
type the following command and check the response
You will get a response something like armv7l or armv8.
ARMv7 and below are 32-bit. AMRv8 introduces the 64-bit instruction set.
Install lshw using the command
apt-get install lshw
Then type the command lshw. You will be able to find the architecture from the response of the command.