I got into a discussion with a girl: when she suggested the number, I said Uh, quite a square and round number. She replied that number is pure triangle, it has nothing square or round in it. I said it has all of them in it and I will prove it to her mathematically. She said game on.

So which approaches exist to represent numbers that can explain this feeling they give?
I've thought I would start relating them to prime numbers but would like a geometrical representation too