What is 1 with 21 zeros called

A 1 followed by 21 zeros (1,000,000,000,000,000,000,000) is called a sextillion in American and modern British English numbering systems. This represents 10^21, placing it in the higher echelons of commonly named large numbers, though it remains millions of orders of magnitude smaller than numbers like googol or the values encountered in advanced mathematics and cosmology.

Sextillion-scale quantities occasionally appear in scientific contexts—for example, there are approximately 7.5 sextillion grains of sand on Earth's beaches, and stars in the observable universe number around 1 sextillion. The number also emerges in computational discussions about data storage capacity projections, cryptocurrency market calculations when expressed in smallest denominations, and national debt figures when considering all global financial obligations combined. Understanding the naming convention—where each step (million, billion, trillion, quadrillion, quintillion, sextillion) represents multiplication by 1,000—helps navigate discussions in astronomy, economics, and data science where these scales naturally occur.