According to the list of approved metric prefixes, a quintillion comes after a quadrillion. A quintillion is a cardinal number represented in the United States by 1 followed by 18 zeros, and a quadrillion is a cardinal number represented in the United States by 1 followed by 15 zeros.
In 1991 the 19th General Conference on Weights and Measures extended its list of approved metric prefixes to reach from one septillion to one septillionth. A septillion is a cardinal number represented in the United States by 1 followed by 24 zeros. Other prefixes on this list include kilo-, which equals 1,000, centi-, which equals 0.01 and mega-, which equals 1,000,000. These prefixes serve as multipliers for the base units in the International System of Units. For example, a 3-km race is a race that is three times 1,000 meters. The prefix for one quintillion is exa-. According to Techandfacts.com, a normal Rubik's cube has over 43 quintillion different possible combinations.