222 (two hundred ndtwenty-two) is the natural number following

221 __NOTOC__ Year 221 (Roman numerals, CCXXI) was a common year starting on Monday (link will display the full calendar) of the Julian calendar. At the time, it was known as the Year of the Consulship of Gratus and Vitellius (or, less frequently, ...

and preceding

223 __NOTOC__ Year 223 ( CCXXIII) was a common year starting on Wednesday (link will display the full calendar) of the Julian calendar. At the time, it was known as the Year of the Consulship of Maximus and Aelianus (or, less frequently, year 976 ' ...

In mathematics

It is a

decimal The decimal numeral system (also called the base-ten positional numeral system and denary or decanary) is the standard system for denoting integer and non-integer numbers. It is the extension to non-integer numbers of the Hindu–Arabic numeral ...

repdigit and a

strobogrammatic number A strobogrammatic number is a number whose numeral is rotationally symmetric, so that it appears the same when rotated 180 degrees. In other words, the numeral looks the same right-side up and upside down (e.g., 69, 96, 1001). A strobogrammatic ...

(meaning that it looks the same turned upside down on a calculator display). It is one of the numbers whose digit sum in decimal is the same as it is in binary. 222 is a noncototient, meaning that it cannot be written in the form ''n'' − φ(''n'') where φ is

Euler's totient function In number theory, Euler's totient function counts the positive integers up to a given integer that are relatively prime to . It is written using the Greek letter phi as \varphi(n) or \phi(n), and may also be called Euler's phi function. In ot ...

counting the number of values that are smaller than ''n'' and relatively prime to it. There are exactly 222 distinct ways of assigning a meet and join operation to a set of ten unlabelled elements in order to give them the structure of a lattice, and exactly 222 different six-edge polysticks.

References

{{DEFAULTSORT:222 (Number) Integers