Harriel added eight rebounds and five assists to his point total.
The Highlanders (1-3) shot nearly 53 percent from the field, making 37 of 70 shots, but Whitman (0-2) hung around thanks to 11 made 3-pointers and the efforts of Ben Eisenhardt who scored 21 points on 7-of-19 shooting while pulling eight rebounds.
Robert Smith was the third player in double figures for UC Riverside with 17 points on 7-of-11 shooting including 3 for 6 from behind the arc. Lucas Devenny scored only three points but had 15 rebounds for the Highlanders.
UC Riverside dominated the paint, outscoring the Missionaries 40-24 and was stellar in the open court, outscoring Whitman 20-5 on fast-break points.