222 (number)
| ||||
|---|---|---|---|---|
| Cardinal | two hundred twenty-two | |||
| Ordinal | 222nd (two hundred twenty-second) | |||
| Factorization | 2 × 3 × 37 | |||
| Greek numeral | ΣΚΒ´ | |||
| Roman numeral | CCXXII | |||
| Binary | 110111102 | |||
| Ternary | 220203 | |||
| Senary | 10106 | |||
| Octal | 3368 | |||
| Duodecimal | 16612 | |||
| Hexadecimal | DE16 | |||
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]
In chemistry
Radon-222 is the most common isotope of radon.
References
- ^ Sloane, N. J. A. (ed.). "Sequence A010785 (Repdigit numbers, or numbers with repeated digits)". The On-Line Encyclopedia of Integer Sequences. OEIS Foundation.
- ^ Sloane, N. J. A. (ed.). "Sequence A018846 (Strobogrammatic numbers: numbers that are the same upside down (using calculator-style numerals))". The On-Line Encyclopedia of Integer Sequences. OEIS Foundation.
- ^ Sloane, N. J. A. (ed.). "Sequence A037308 (Numbers n such that (sum of base 2 digits of n) = (sum of base 10 digits of n))". The On-Line Encyclopedia of Integer Sequences. OEIS Foundation.
- ^ Sloane, N. J. A. (ed.). "Sequence A005278 (Noncototients: n such that x-phi(x) = n has no solution)". The On-Line Encyclopedia of Integer Sequences. OEIS Foundation.
- ^ Sloane, N. J. A. (ed.). "Sequence A006966 (Number of lattices on n unlabeled nodes)". The On-Line Encyclopedia of Integer Sequences. OEIS Foundation.
- ^ Sloane, N. J. A. (ed.). "Sequence A019988 (Number of ways of embedding a connected graph with n edges in the square lattice)". The On-Line Encyclopedia of Integer Sequences. OEIS Foundation.