222 (number)

Last updated
← 221 222 223 →
Cardinal two hundred twenty-two
Ordinal 222nd
(two hundred twenty-second)
Factorization 2 × 3 × 37
Divisors 1, 2, 3, 6, 37, 74, 111, 222
Greek numeral ΣΚΒ´
Roman numeral CCXXII, 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]

References

  1. ↑ Sloane, N. J. A. (ed.). "SequenceA010785(Repdigit numbers, or numbers with repeated digits)". The On-Line Encyclopedia of Integer Sequences . OEIS Foundation.
  2. ↑ Sloane, N. J. A. (ed.). "SequenceA018846(Strobogrammatic numbers: numbers that are the same upside down (using calculator-style numerals))". The On-Line Encyclopedia of Integer Sequences . OEIS Foundation.
  3. ↑ Sloane, N. J. A. (ed.). "SequenceA037308(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.
  4. ↑ Sloane, N. J. A. (ed.). "SequenceA005278(Noncototients: n such that x-phi(x) = n has no solution)". The On-Line Encyclopedia of Integer Sequences . OEIS Foundation.
  5. ↑ Sloane, N. J. A. (ed.). "SequenceA006966(Number of lattices on n unlabeled nodes)". The On-Line Encyclopedia of Integer Sequences . OEIS Foundation.
  6. ↑ Sloane, N. J. A. (ed.). "SequenceA019988(Number of ways of embedding a connected graph with n edges in the square lattice)". The On-Line Encyclopedia of Integer Sequences . OEIS Foundation.


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