Post a number with an interesting property

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Today I was bored so I decided to find interesting properties of the number 23.

I found this property:

23^2=529
23x32=736

If you take the digital sum you'll get 16, in both cases.

23 has the property that if you multiply it by it's digital inverse and square it and then add the digits for both of those, it'll be the same number.

Post a number with an interesting property.

The first one that came to mind: 2+2=2x2=2².

All numbers are interesting. So you just have to pick any number and find an interesting property.

I really hate the number 6.

But 6 is a perfect number. If you add up the factors of six you'll get,

1+2+3+6=12=2x6

In some definitions the factor, 6, is left out.

This number is a really awesome number. If you take this number to the power of 3^n for some n (if the Riemann Hypothesis is true) and then you round it to the nearest whole positive integer, it will always be a prime.

Here is the sequence:

2, 11, 1361, 2521008887, 16022236204009818131831320183, 4113101149215104800030529537915953170486139623539759933135949994882770404074832568499

Mill's constant=1.3063778838630806904686144926026057129167845851567136443680537599664340537668...

Also, if you take the 3^n-th root of the prime generating by that sequence, it tends to Mill's constant.

Evaluate the 81st root of 2521008887 and you'll see what I mean.

2015 (this year) is the mean of the first 77 squares.

2015=(1^2+2^2+...+77^2)/77

I find it interesting that every number has infinitely many digits after the point.
1.0000000000... has the same after-digit lengh as pi, we just assume that 1 is 1.0 with infinitely many 0s and not necissarily think about it.

So ...if 495 is your "property" that would mean that 495 is an example of real estate.

So that would mean that the square root of negative 495 would be "imaginary estate".

91

91 can be expressed as the sum of two cubes (integers) in two different ways.

91= 6^3 + (−5)^3 = 4^3 + 3^3

Not only that. But 91=1+7+2+9 and 1729 is another number that can be expressed as the sum of two cubes in two different ways.

1729=1^3+12^3=9^3+10^3

Also, if you multiply 91 by it's digital inverse (19) it will be 1729.

91x19=1729

That is just really amazing!

1729 is also the product of three distinct primes (sphenic number).

It is also a Carmichael number. Meaning it is an exception to Fermat's primality test. Watch Numberphile for an explanation.