How to know you're running 32-bit or 64-bit ubuntu ?
There is a nice and simple command line program called uname that tells the current bit version
uname - m
in terminal and hit enter.
If the response is i686, you have a 32-bit version of Linux.
If the response is x86_64, you have a 64-bit version of Linux.
If you want to know more details like Kernel version, Time stamp etc..