217 (number)

This article is about the numerical value. For other uses, see 217 (disambiguation).

← 216 217 218 →
← 210 211 212 213 214 215 216 217 218 219 → List of numbers Integers ← 0 100 200 300 400 500 600 700 800 900 →
Cardinal	two hundred seventeen
Ordinal	217th (two hundred seventeenth)
Factorization	7 × 31
Greek numeral	ΣΙΖ´
Roman numeral	CCXVII, ccxvii
Binary	110110012
Ternary	220013
Senary	10016
Octal	3318
Duodecimal	16112
Hexadecimal	D916

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. ^[1] It is both the sum of two positive cubes and the difference of two positive consecutive cubes in exactly one way: ${\displaystyle 217=6^{3}+1^{3}=9^{3}-8^{3}}$. When written in binary, it is a non-repetitive Kaprekar number. ^[2] It is also the sum of all the divisors of 100 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

References

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