Sextillion

A sextillion is a number: a one followed by 21 zeros. Written out in full, that is 1,000,000,000,000,000,000,000. It is a thousand times as large as a quintillion and a billion times as large as a trillion. In short notation it is written as 10^21, spoken as “ten to the power of twenty-one.” This means the ten is multiplied by itself 21 times. In the American numbering system, the sextillion follows a fixed pattern that alternates in steps of a thousand: million, billion, trillion, quadrillion, quintillion, sextillion.

Why we need such large numbers at all

In everyday life, no one encounters a sextillion. Even national debts move in the range of trillions, which is six zeros less. But as soon as you count things that are very small and very numerous, you quickly reach this range. A grain of sand is tiny, but all the grains of sand on Earth together roughly amount to a number in this order of magnitude.

In technology, the most important case is computing power. Modern supercomputers manage more than a sextillion computing operations per second. Experts call this zettaflops. Data volumes also reach this magnitude: a zettabyte is a sextillion bytes, and global data traffic has long been measured in zettabytes.

There is also an important source of error here. In German, a sextillion is called “Trilliarde,” while the German word “Trillion” actually refers to what English speakers call a quintillion. Anyone translating between German and English news can easily miscalculate by a factor of a thousand or more. When it comes to monetary amounts and performance figures, this is a serious difference.

The structure of the long ladder

The American system is called the short scale. Each name ending in “-illion” stands for a thousand times the previous “-illion.” A million is 10^6, a billion is 10^9, a trillion is 10^12. In the long scale used in German-speaking countries, there are additional number words ending in “-illiard” placed in between, each exactly a thousand times as large as its predecessor. This is how the sextillion arises as 10^21.

More practical is notation using powers of ten. Instead of counting zeros, you write 10^21 and immediately know how many digits the number has. This makes multiplication simple: you just add the exponents. A billion (10^9) times a trillion (10^12) equals 10^21, in other words a sextillion.

In computing, there is additionally the prefix zetta for 10^21. It belongs to the International System of Units, just like kilo for a thousand or mega for a million. A zettabyte, a zettaflop, a zettawatt-hour – all three contain the factor of a sextillion. When it comes to storage sizes, there is a subtlety: computers calculate in powers of two, which is why alongside the zettabyte there is also the slightly larger zebibyte.

Sextillions in tech news

The term is most often encountered in reports about supercomputers and AI data centers. After the exascale era, in which computers achieve a quintillion operations per second, the next threshold is the zettascale. It stands at a sextillion operations per second. Experts expect this to be reached in the 2030s.

A second area is data statistics. Reports on the global internet now cite figures of more than a hundred zettabytes per year, meaning more than a hundred sextillion bytes. Such magnitudes also appear in energy consumption when converting global demand into joules.

A typical misconception: many people believe the sextillion is the record-holder among number words. In fact, the ladder continues upward through septillion, octillion, and much higher still. In natural science, 10^21 is actually rather middling. The number of atoms in a small drop of water falls exactly in this range.