The general impression I get from what little is for certain quantified about Azathoth is that it is huge (bigger than a galaxy, big enough for multiple galaxies to orbit it), totally unintelligent (or at the very least in a kind of semi-perpetual dreamless sleep), and that the echos of its ancient thoughts control everything, everywhere, all the time, even though these thoughts often (most of the time), make absolutely no sense at all. And by 'everything everywhere' I mean to say 'all realities everywhere period'.