What's the most beautiful number in the world?

SW-User

69

helenS · 36-40, F

π

DrWatson · 70-79, M

There are so many different criteria one could use.

Six is the first "perfect number". It is the sum of all it's divisors (other than itself).

That is, 6 is divisible by 1, 2, and 3, and

6 = 1 + 2 + 3

Apart from my thinking that being perfect is a pretty property for numbers to have, what I also find beautiful is the doorway this opens to other mathematical questions.

There are about 50 numbers that are known to be perfect. ( The next one after 6 is 28. You can check for yourself that it is perfect.) Nobody knows whether the list of perfect numbers goes on forever or whether there is a greatest perfect number.

All the known perfect numbers are even. Does an odd perfect number exist? Nobody knows.

And there is a beautiful connection between perfect numbers and certain prime numbers known as Mersenne primes, but I won't go into that here.

Punxi · F

3.14

DrWatson · 70-79, M

I think a lot of responders are confusing "number" with "numeral."

For example, people seem to like the numeral for sixty nine. That is, the symbols we use to express that number apparently appeal to people who responded here, either because their shape denotes something sexual of because of the symmetries. But the actual number is not the symbol. For example, the ancient Romans would have written it as LXIX. Sixty nine pieces of silver meant the same thing to them as it does to us, and I am sure they practiced oral sex, but I don't think they would think sixty nine was a particularly interesting number.

The number is the quantity. The numeral is how we write the number. "69" and "LXIX" are two different numerals for the same number.

So the most beautiful number in the world, if there is such a thing, would be a number with beautiful mathematical properties. This would have nothing to do with what marks we make with pencil and paper to denote that number by a numeral.