217 is the natural number

Natural number

In mathematics, the natural numbers are the ordinary whole numbers used for counting and ordering . These purposes are related to the linguistic notions of cardinal and ordinal numbers, respectively...

 following 216

216 (number)

216 is the natural number following 215 and preceding 217.Since 216 = 3^3 + 4^3 + 5^3 = 6^3, it is the smallest cube that's also the sum of three cubes . It is also the sum of a twin prime...

 and preceding 218

218 (number)

218 is the natural number following 217 and preceding 219.*Mertens function = 3, a record high.*218 is both nontotient and noncototient....

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Here are the representations of 217 in other numeral system

Numeral system

A numeral system is a writing system for expressing numbers, that is a mathematical notation for representing numbers of a given set, using graphemes or symbols in a consistent manner....

s:

217 base	representation of 217
2	11011001
8	331
16	D9

217 is a centered hexagonal number

Centered hexagonal number

A centered hexagonal number, or hex number, is a centered figurate number that represents a hexagon with a dot in the center and all other dots surrounding the center dot in a hexagonal lattice....

, a 12-gonal number

Polygonal number

In mathematics, a polygonal number is a number represented as dots or pebbles arranged in the shape of a regular polygon. The dots were thought of as alphas . These are one type of 2-dimensional figurate numbers.- Definition and examples :...

, a centered 36-gonal number, and a Blum integer

Blum integer

In mathematics, a natural number n is a Blum integer if n = p×q is a semiprime for which p and q are distinct prime numbers congruent to 3 mod 4. That is, p and q must be of the form 4t+3, for some integer t. Primes of this form are referred to as Blum primes. This means that the factors of a Blum...

. It is both the sum of two positive cubes and the difference of two positive consecutive cubes in exactly one way: . When written in binary, it is a non-repetitive Kaprekar number

Kaprekar number

In mathematics, a Kaprekar number for a given base is a non-negative integer, the representation of whose square in that base can be split into two parts that add up to the original number again. For instance, 45 is a Kaprekar number, because 45² = 2025 and 20+25 = 45. The Kaprekar numbers are...

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See also

• The year 217
  217
  Year 217 was a common year starting on Wednesday of the Julian calendar. At the time, it was known as the Year of the Consulship of Praesens and Extricatus...
  
  
• 217 is the area code for central Illinois
  Illinois
  Illinois is the fifth-most populous state of the United States of America, and is often noted for being a microcosm of the entire country. With Chicago in the northeast, small industrial cities and great agricultural productivity in central and northern Illinois, and natural resources like coal,...
  
  
• In Stephen King's
  Stephen King
  Stephen Edwin King is an American author of contemporary horror, suspense, science fiction and fantasy fiction. His books have sold more than 350 million copies and have been adapted into a number of feature films, television movies and comic books...
  
   novel "The Shining
  The Shining (novel)
  The Shining is a 1977 horror novel by American author Stephen King. The title was inspired by the John Lennon song "Instant Karma!", which contained the line "We all shine on…". It was King's third published novel, and first hardback bestseller, and the success of the book firmly established King...
  
  ", room 217 plays a central part of the story as it is haunted.
• When read upside-down on a digital clock, it appears to say "LIZ"