# Un-Interesting Numbers

20 November 2011
Many numbers are interesting for their specific properties, for example:

2
the smallest even prime number
2! = 2
a Fibonacci number

25
= 5 x 5  - A square.
= 1 + 3 + 5 + 7 + 9
= 3 + 4 + 5 + 6 + 7
= 3 squared + 4 squared - A square number which is the sum of two square numbers.

163
a prime number
the smallest number impossible to make with three darts

Some numbers are ‘uninteresting’ because they don’t possess any properties similar to the above.

There is an anecdote about the mathematician Ramanujan and interesting (or uninteresting) numbers.  Ramanujan was an outstanding Indian mathematician with little formal training who worked with Hardy at Cambridge for nearly five years from 1914, before dying of illness in 1920 at the age of 32.
Hardy said of Ramanujan,
“ I remember once going to see him when he was ill at Putney. I had ridden in taxi cab number 1729 and remarked that the number seemed to me rather a dull one, and that I hoped it was not an unfavorable omen. "No," he replied, "it is a very interesting number; it is the smallest number expressible as the sum of two cubes in two different ways."
These two ways are
1729 = 13 + 123 = 93 + 103

Which numbers do you think are uninteresting? What is the smallest uninteresting number?

Perhaps there is no smallest uninteresting number, because that in itself would make the number interesting…