The word appears 2 times.
I don't believe it was necessary as the book is supposedly post-modern and could have easily avoided this. Ah well.
"Hell now." He gave her an insider's wink. "Got this little factory down outside of San Diego," he told her, "got a dozen of your niggers, say, they can sure turn them old armbands out. You'd be amazed how that little number's selling. I took some space in a couple of girlie magazines, and I had to hire two extra niggers last week just to take care of the mail."