the number is just the version of the config, e.g. if you conf t and add something new and then write mem, the value will change to 5.
I am not sure I follow what you mean when you say that the other lines dont' tell you it's a controller - whilst the Aruba config looks something like any old switch or router, there are tokens all the way through it that tell you it's an Aruba config (e.g. the presence of something called apprf or sys-ap-role), but, yes, you could probably use the presence of that line "controller <Number>" as a way to tell it's an Aruba controller.
or whatever script you are using to collect it, could possibly run "show version | include MODEL" first, then that will tell you explictly.