What makes the number 2,520 so unique?
From: Anitha @ Fidelity (Bangalore)

It's the lowest number that is evenly divisible by every single digit number.Here's a breakdown of how 2,520 divides into each digit from 1 to 9:
number ---divided by ---equals
-----------------------------------------------
2,520-------------1-------------2,520
2,520-------------2-------------1,260
2,520-------------3-------------840
2,520-------------4-------------630
2,520-------------5-------------504
2,520-------------6-------------420
2,520-------------7-------------360
2,520-------------8-------------315
2,520-------------9-------------280
NOTE
1 x 2 x 3 = 6. Six is the smallest number divisible by 1, 2 and 3.
1 x 2 x 3 x 2 = 12. Twelve is the smallest number divisible by the 1, 2, 3 and 4.
1 x 2 x 3 x 2 x 5 x 7 = 420. This number is divisible by 1, 2, 3, 4, 5, 6 and 7.
1 x 2 x 3 x 2 x 5 x 7 x 2 x 3 = 2,520.