After trillionaire, there is the quadrillionaire (tri = three and quad = four, etc.), and after that is the quintillionaire (because quint = five).
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)
Extremely popular?If someone had 1 x 1019 (which would be a 20 digit number) pounds then they would have 10 quintillion pounds! I suppose this would make them a quintillionaire!Of course this terminology assumes you are using the American / seemingly "modern British" definitions and not the traditional English definition.