sextillion

num

Etymology: From Classical Latin sextus (“sixth”) + -illion; originally the sixth power of a million, 10³⁶. Compare slightly earlier quintillion, Middle French sixlion (1484) and French sextillion (1765). First attested in 1689 in John Locke’s An Essay Concerning Human Understanding (see the quotation).

1. A trillion billion: 1 followed by 21 zeros, 10²¹.
2. A million quintillion: 1 followed by 36 zeros, 10³⁶.

   “[W]e take now to name them by Millions of Millions of Millions, it is hard to go beyond eighteen, or at moſt four and twenty decimal Progreſſions, without confuſion. But to ſhew how much diſtinct Names conduce to our well reckoning, or having uſeful Ideas of Numbers, let us ſet all these following Figures in one continued Line, as the Marks of one Number: v. g. Nonilions. 857324. Octilions. 162486. Septilions. 345896. Sextilions. 437916. Quintilions. 423147. Quatrilions. 248106. Trilions. 235421. Bilions. 261734. Milions. 368149. Vnites. 623137.”