217 (two hundred
ndseventeen) is the
natural number
In mathematics, the natural numbers are the numbers 0, 1, 2, 3, and so on, possibly excluding 0. Some start counting with 0, defining the natural numbers as the non-negative integers , while others start with 1, defining them as the positive in ...
following
216
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Year 216 ( CCXVI) was a leap year starting on Monday of the Julian calendar. At the time, it was known as the Year of the Consulship of Sabinus and Anullinus (or, less frequently, year 969 ''Ab urbe condita''). The denomination 216 f ...
and preceding
218.
In mathematics
217 is a
centered hexagonal number
In mathematics and combinatorics, a centered hexagonal number, or centered hexagon number, is a centered polygonal number, centered figurate number that represents a hexagon with a dot in the center and all other dots surrounding the center dot ...
, a
12-gonal number, a
centered 36-gonal number, a
Fermat pseudoprime to
base 5
Quinary (base 5 or pental) is a numeral system with five as the base. A possible origination of a quinary system is that there are five digits on either hand.
In the quinary place system, five numerals, from 0 to 4, are used to represent an ...
, 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:
. When written in binary, it is a non-repetitive
Kaprekar number
In mathematics, a natural number in a given number base is a p-Kaprekar number if the representation of its square in that base can be split into two parts, where the second part has p digits, that add up to the original number. For example, in ...
.
The non-repetitive Kaprekar binary numbers in decimal
OEIS It is also the sum of all the divisor
In mathematics, a divisor of an integer n, also called a factor of n, is an integer m that may be multiplied by some integer to produce n. In this case, one also says that n is a '' multiple'' of m. An integer n is divisible or evenly divisibl ...
s of .
See also
* 217, the year
References
Integers
ca:Nombre 210#Nombres del 211 al 219
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