Factorial of six and the birth of HD

720 = 6 × 5 × 4 × 3 × 2 × 1: the number of ways to arrange 6 objects. Factorial numbers are the foundation of combinatorics, probability and quantum statistics.

Electrons and protons (spin-½ particles) return to their original state only after a 720° rotation, not 360°. This defies intuition and is a fundamental property of matter.

720 lines — the first HD standard (HD Ready). YouTube introduced 720p in 2008, permanently changing how humanity watches video. The pixel era began here.

720 has 30 divisors — more than any smaller number. This is a 'highly composite number' per Ramanujan: a record-holder for divisor count among numbers of its size.