285

285 is a natural number that follows 284 and precedes 286. In mathematics, it is an odd composite number.

Its prime factorization is 285 = 3 × 5 × 19. The divisors of 285 are 1, 3, 5, 15, 19, 57, 95, and 285. The sum of its proper divisors is 195, which is less than 285, so 285 is a deficient number.

In various numeral systems, 285 is represented as decimal 285, binary 100011101, octal 435, and hexadecimal 11D. In Roman numerals, 285 is written as CCLXXXV.

Historically, the year 285 CE falls within the late phase of the Crisis of the Third Century in the Roman Empire, a period marked by military and political turmoil as the empire faced internal and external pressures.

Overall, 285 serves as a reference point in number theory and as a calendar year within ancient Roman history, with standard representations across several base systems and the Roman numeral tradition.