quintillionare
There is currently no quadrillionaire, however it has been estimated that Bill Gates ( Founder of Microsoft) will become a quadrilloinaire before the age of 65 (Required Retirement Age).
After trillionaire, there is the quadrillionaire (tri = three and quad = four, etc.), and after that is the quintillionaire (because quint = five).
trillionaire isn't a word. after millionaire its multi millionaire but if you wanted to go down that route it would be quadrillionaire.
Certainly, there have been many Quadrillionaires, though not in US$. In April of 2009, Zimbabwe printed the largest currency note of the last few decades '100 Trillion Dollars'. The day it was released it would buy approximately 3 eggs, at that price a Quadrillionaire could afford 3 dozen OS so eggs. Just search Hyperinflation.
Oh honey, that's an easy one. A number with 16 zeros behind it is called a quadrillion. Yep, you heard me right, quadrillion. So next time you're counting your imaginary millions, just add a few more zeros and you'll be in quadrillionaire territory.
The wealth line up is as follows: Millionaire (6 zeros) Billionaire (9 zeros) Trillionaire (12 zeros) Quadrillionaire (15 zeros) Quintillionaire (18 zeros) Sextillionaire (21 zeros) Septillionaire (24 zeros) Octillionaire (27 zeros) Nonillionaire (30 zeros)