842

842 is an integer in the decimal numbering system. It is even and composite, lying between 841 and 843. In mathematics, it is commonly noted for being the product of two primes, making it a semiprime.

Prime factorization: 842 = 2 × 421, with 421 prime. Divisors: 1, 2, 421, 842. The totient φ(842) = 420, and the sum of all divisors σ(842) = 1266. The sum of proper divisors is 424, so 842 is a deficient number.

Representations: In binary, 1101001010; in hexadecimal, 0x34A; in Roman numerals, DCCCXLII.

In historical contexts, 842 can designate a calendar year in both BCE and CE. In other domains, 842 may appear as an identifier (for example, model numbers or route numbers) depending on the governing system.