217 (number)
{{about|the numerical value|other uses|217 (disambiguation)}}
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217 (two hundred [and] seventeen) is the natural number following 216 and preceding 218.
In mathematics
217 is a centered hexagonal number, a 12-gonal number, a centered 36-gonal number, a Fermat pseudoprime to base 5, and a Blum integer.[http://www.virtuescience.com/217.html The Number 217], Virtue Science 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.[http://oeis.org/A163205 The non-repetitive Kaprekar binary numbers in decimal], OEIS It is also the sum of all the divisors of {{num|100}}.
See also
- 217, the year