217 (two hundred [and] seventeen) is the natural number following 216 and preceding 218.
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.
[1] 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.
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