217 (number)

Template:About Template:Infobox 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 Template:Num and the number of week-month combinations in the Gregorian calendar (Monday the 1st, Tuesday the 2nd, Wednesday the 3rd, etc.).

See also

• 217, the year