Английская Википедия:222 (number)
Шаблон:Other uses Шаблон:Infobox number 222 (two hundred [and] twenty-two) is the natural number following 221 and preceding 223.
In mathematics
It is a decimal repdigit[1] and a strobogrammatic number (meaning that it looks the same turned upside down on a calculator display).[2] It is one of the numbers whose digit sum in decimal is the same as it is in binary.[3]
222 is a noncototient, meaning that it cannot be written in the form n − φ(n) where φ is Euler's totient function counting the number of values that are smaller than n and relatively prime to it.[4]
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,[5] and exactly 222 different six-edge polysticks.[6]
References
