530

530 = 2 x 5 x 53.

530 is the sum of the first three perfect numbers: 530 = 6 + 28 + 496.

530 is 1000010010 in base 2 (binary).

530 has two representations as a sum of two squares: 530 = 1² + 23² = 13² + 19².

530 is a divisor of 23⁴ - 1.

Halley's Comet was visible from Earth in the year 530.

Source: What's Special About This Number?