406

406 = 2 x 7 x 29.

406 is the 28th triangular number. It is the sum of the first 28 positive integers.

406 is a centered nonagonal number.

406 is the number of ways to tile a 3 x 17 rectangle with 3 x 1 rectangles.

406 = 1³ + 4³ + 5³ + 6³ = 1³ + 2³ + 3³ + 3³ + 7³.

406 is 626 in base 8 and 210 in base 14.

406 is the title of a poem by John Boyle O'Reilly.

Source: What's Special About This Number?