216 (number)

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216 is the natural number following 215 and preceding 217.

List of numbers — Integers ← 0 100 200 300 400 500 600 700 800 900 →
Cardinal	Two hundred [and] sixteen
Ordinal	216th
Factorization	$2^3 \cdot 3^3$
Roman numeral	CCXVI
Binary	11011000
Hexadecimal	D8

Since $216 = 3 3 + 4 3 + 5 3 = 6 3$ , it is the smallest cube that's also the sum of three cubes (Plato was among the first to notice this, and mentioned it in Book VIII of Republic). It is also the sum of a twin prime (107 + 109). But since there is no way to express it as the sum of the proper divisors of any other integer, it is an untouchable number.

This multiplicative magic square

$\begin{pmatrix} 2 & 9 & 12\\ 36 & 6 & 1\\ 3 & 4 & 18 \end{pmatrix}$

has magic constant 216.

In base 10, it is a Harshad number.

[edit] In other fields

The 216 colors formed by a 6×6×6 color cube are sometimes known as the web-safe color palette.
ISO 216 is the ISO's standard for paper sizes.
In the film Pi, a mysterious 216-digit number represents the name of God.
As six cubed, 216 is also symbolic of the Mark of the Beast in Christianity. This has been expressed in the Left Behind series.
216 is also the phone area code for the Cleveland, Ohio region and some surrounding suburbs in Cuyahoga County.