Mike Tyson is down to fight Jake Paul ... in what'd be one of the most talked-about boxing matches of all time.
There's just one catch -- Iron Mike wants a BILLION dollars.
55-year-old Tyson made the comments on his "Hotboxin'" podcast this week ... when his convo with boxer Jermell Charlo and Boston Celtics legend Paul Pierce turned to a rumored fight against Jake.
Pierce said he heard Mike was going to fight Jake, but Tyson seemed to be unaware of the rumor.