290

290 is a natural number that follows 289 and precedes 291. It is used as a basic identifier in mathematics, counting, and various labeling schemes.

In mathematics, 290 is a composite number with prime factorization 2 × 5 × 29. Its divisors are 1, 2, 5, 10, 29, 58, 145, and 290. The number is square-free, since no prime factor repeats. The sum of its proper divisors is 250, which means 290 is a deficient number. The Euler totient function applied to 290 yields φ(290) = 112, reflecting the count of integers up to 290 that are relatively prime to 290.

In numeral systems, 290 is written as CCXC in Roman numerals, 0x122 in hexadecimal, and 100100010 in binary. In decimal, its digits sum to 11, but this does not render 290 a Harshad number in base 10.

The 290th day of a year depends on leap years: in a non-leap year, the 290th day is October 17; in a leap year, October 16. This aligns with the typical day-count progression through the calendar.

Beyond pure mathematics, 290 can appear as an identifier in various contexts, such as model numbers, product codes, or highway designations, where the meaning is defined by the surrounding system or jurisdiction.