Prime numbers have no factors other than themselves and 1. e.g. 7 = 1 x 7
Other numbers can be reduced in only one way to their prime factors. e.g. 6 = 2 x 3, 8 = 2 x 2 x 2
These pictures show the numbers from 2 up, arranged into their prime factors, using various sized rows to bring out different features. The logarithm of the heights is used, otherwise the later rows would be vastly taller than the earlier ones.

Primes and prime factors up to 431, 72 = 3 x 3 x 2 x 2 x 2 to a row.

Up to 319

Up to 839

Up to 839

Up to 839, 60 per row

Up to 719

Up to 719

Up to 503

Up to 503

Rows of 70 = 2 x 5 x 7

Up to 2519, 210 to a row. This and the next have primes in white, everything else grayed out.

Up to 1889, rows of 210 = 2 x 3 x 5 x 7. This uses a log log for height, so the primes appear shorter than composite numbers.