Oprah is not going to go out on top.

Last week was the lowest rated in the 24-year history of her show according to Nielsen.

“The Oprah Winfrey Show” has been in reruns for several weeks but compared to the same week last year — which was all reruns, too — the ratings were down an eye-watering 23 percent, according to tvbythenumbers.com, a ratings Web site.

The audience for Oprah was just over 4 million viewers — the lowest it has ever been since the show first went on the air in 1986.

The bottomed-out ratings have had little practical effect on the daytime talk show against which all the others are measured. Her ads remain the highest-priced on afternoon TV and getting big-name guests is still no problem.

The falling audience numbers may be a reaction to Winfrey’s announcement earlier this year that 2011 would be her show’s final season.

Viewers have begun to disconnect from her in anticipation of her departure from five-days-a-week TV.

Insiders have been saying for a while that Oprah’s influence may be at an all-time high, but her impact on TV is starting to fade badly.

This week, Forbes named Oprah its No. 1 most powerful celebrity for the fourth time and reported that she has earned a staggering $315 million over the last year.