6420

6420 = 2 x 2 x 3 x 5 x 107.

6420 is a number with even decimal digits in decreasing order (A119261).

6420 is a number n such that n and the square of n (41,216,400) use only the digits 0, 1, 2. 4, and 6.

6420 is the number of balls in a hexagonal pyramid of height 29 taken from hexagonal close-packing (A019298).

The John Deere 6420 was a popular tractor model.

Source: On-Line Encyclopedia of Integer Sequences