Fascinating interview with Daniel Tammet the Savant.  He who can sit down and recite Pi to 22 thousand places.

LEHRER: How were you able to recite from memory the first 22,514 numbers of Pi? And do you have advice for people looking to improve their own memory?

TAMMET: As I have already mentioned, numbers to me have their own shapes, colors and textures. Various studies have long demonstrated that being able to visualize information makes it easier to remember. In addition, my number shapes are semantically meaningful, which is to say that I am able to visualize their relationship to other numbers. A simple example would be the number 37, which is lumpy like oatmeal, and 111 which is similarly lumpy but also round like the number three (being 37 x 3). Where you might see an endless string of random digits when looking at the decimals of Pi, my mind is able to “chunk” groups of these numbers spontaneously into meaningful visual images that constitute their own hierarchy of associations.

There is a striking BBC show that went in depth with Daniel on his capabilities and his most unusual characteristic, which is his normalcy.  Most Savants are prefaced with the word idiot: "idiot savant".  Meaning they have strengths in specific areas of intelligence at the expense of others, often leaving them debilitated and unable to function normally in society.  Daniel has no (or very little) debilitating issues.

See video here: Savant: The boy who saw numbers