There is no such event on mobile devices – apps are normally full screen, which means that if a touch goes off the edge of your app boundaries it has left the device. It cannot tell whether your finger has been lifted as there are no touch detectors it can use, on e.g. the bezel.
There are also split-screen apps on e.g. recent iPad models, but in most cases nothing changes wrt touch events - they treat it as being full screen, just with odd dimensions and resize events. There is a way to do drag and drop between apps but not using Actionscript.