What’s the most damage you can do in a single attack

What's the most damage a single attack could do (theoretically) with maxed out stats (level 9,999, relevant attack stat(s) at 9,999,999 points), beneficial item innocents, a max-level skill ect? I know anything that does even 1 billion damage will kill any enemy (normally) but I'm curious as to how high the numbers will go.

Is this something that can/has been calculated? I know I've seen the damage indicator go into the billions at least, so I also wonder if the max damage is capped at say 9,999,999,999 in one hit or if it's limited by the actual amount of damage feasable due to normal game mechanics.