217 (number)

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. It is both the sum of two positive cubes and the difference of two positive consecutive cubes in exactly one way: $$217 = 6^3 + 1^3 = 9^3 - 8^3$$. When written in binary, it is a non-repetitive Kaprekar number. It is also the sum of all the divisors of.