http://numbersapi.com/1729/math "1729 is a plain old number." Can't recognize Hardy-Ramanujan number? Also the smallest perfect number: http://numbersapi.com/6/math "6 is the smallest number of distinct isosceles right triangles that will tile an isosceles right triangle."
> 1729 is the smallest number representable in two different ways as a sum of two positive cubes, as Ramanujan stated on the spot.