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222 (number)

← 221 222 223 →
Cardinaltwo hundred twenty-two
Ordinal222nd
(two hundred twenty-second)
Factorization2 × 3 × 37
Greek numeralΣΚΒ´
Roman numeralCCXXII
Binary110111102
Ternary220203
Quaternary31324
Quinary13425
Senary10106
Octal3368
Duodecimal16612
HexadecimalDE16
VigesimalB220
Base 366636

222 (two hundred [and] twenty-two) is the natural number following 221 and preceding 223.

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 unlabeled 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.). "Sequence A010785 (Repdigit numbers, or numbers with repeated digits)". The On-Line Encyclopedia of Integer Sequences. OEIS Foundation.
  2. ^ 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.
  3. ^ 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.
  4. ^ 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.
  5. ^ Sloane, N. J. A. (ed.). "Sequence A006966 (Number of lattices on n unlabeled nodes)". The On-Line Encyclopedia of Integer Sequences. OEIS Foundation.
  6. ^ 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.