20839

20839 is a minor planet that orbits the Sun in the central region of the asteroid belt between Mars and Jupiter. It was discovered on 12 March 1998 by the Lincoln Near‑Earth Asteroid Research (LINEAR) program at the White Sands Missile Range in New Mexico, United States. The provisional designation assigned to this object was 1998 AB, which reflects its month of discovery and the order of its identification within that month. After its orbit was confirmed over several years of observation, the asteroid received the official number 20839 and was later named "Oren" in honour of a notable astronomer.

The orbit of 20839 has a semi‑major axis of approximately 2.4 astronomical units, placing it firmly within the middle main belt. Its orbital period is roughly 3.7 Earth years, and its orbit has a modest eccentricity of 0.10 and an inclination of about 5 degrees relative to the ecliptic plane. Spectral analysis indicates a stony S‑type composition, common among inner and middle belt asteroids, suggesting a silicate‑rich surface.

Photometric observations conducted by the Lowell Observatory in 2005 determined a rotation period of about 5.3 hours, with a variation in brightness of 0.22 magnitudes, implying a somewhat elongated shape. The absolute magnitude of 20839 is 15.0, which, combined with typical albedo assumptions for S‑type asteroids, yields an estimated diameter of 4 to 5 kilometers. No significant close approaches to Earth have been recorded, and the object remains a typical background member of the main belt population.