Yes, quintillion is a real number. In the United States and many other countries, a quintillion is defined as a one followed by 18 zeros, or 1,000,000,000,000,000,000. In numerical form, it is expressed as 1018.
The term ‘quintillion’ comes from the Latin ‘quintus’, meaning five, and ‘illion,’ which is a suffix used in large number terms. This creates a logical sequence from million (one million) to billion (one billion) to trillion (one trillion), and then to quintillion.
Quintillion is used in various fields such as mathematics, economics, and science when dealing with very large quantities. Overall, quintillion is a standardized and accepted term in number systems, particularly in the short scale system predominantly used in the U.S.