550

550 is a natural number that follows 549 and precedes 551. In mathematics it is an even composite number with prime factorization 2 × 5^2 × 11. The sum of all divisors of 550 is 1116, so the sum of its proper divisors is 566, which makes 550 an abundant number. In common bases, 550 is written as 1000100110 in binary and as 0x226 in hexadecimal. Its Roman numeral value is DL.

In color science and optics, 550 nanometers corresponds to a green region of the visible spectrum, near the center of the green wavelengths perceived by the human eye.

A notable everyday usage of the number 550 is in paracord. 550 cord refers to a lightweight nylon kernmantle rope rated to about 550 pounds of break strength and widely used in survival gear and outdoor equipment.

Geographically and in transportation, U.S. Route 550 is a U.S. highway located in southwestern Colorado. The route is best known for the stretch commonly called the Million Dollar Highway, which runs between Ouray and Silverton and is noted for its steep grades and scenic mountain corridors.

Historically, 550 can designate a calendar year (550 CE), placing it in the early 6th century and within the broader context of late antiquity in various regions.

In postal geography, the 550 prefix is used for ZIP codes in portions of Minnesota, reflecting its role in the United States postal system.