So I was keen to confirm the "bitness" of my AIX 7.1 box ( a p710 ), so a quick Google search brought me to this: -
$ getconf KERNEL_BITMODE
64
64
$ getconf HARDWARE_BITMODE
64
64
$ oslevel -q
Known Maintenance Levels
------------------------
7.1.0.0
Known Maintenance Levels
------------------------
7.1.0.0
Nice :-)