217 (number)

← 216 217 218 →
← 200 210 220 230 240 250 260 270 280 290 → List of numbers — Integers ← 0 100 200 300 400 500 600 700 800 900 →
Cardinal	two hundred seventeen
Ordinal	217th (two hundred and seventeenth)
Factorization	7 × 31
Roman numeral	CCXVII
Binary	110110012
Ternary	220013
Quaternary	31214
Quinary	13325
Senary	10016
Octal	3318
Duodecimal	16112
Hexadecimal	D916
Vigesimal	AH20
Base 36	6136

217 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: $217 = 6^3 + 1^3 = 9^3 - 8^3$. When written in binary, it is a non-repetitive Kaprekar number.^[2]

See also

• 217, the year

References

1. The Number 217, Virtue Science
2. The non-repetitive Kaprekar binary numbers in decimal, OEIS