I hadn't read this in about 20 years - I wanted to see if it was as good as I remembered. Unfortunately, no... It's a bit dated (mentions microfiche!) and Heinlein mentions himself several times in the book, which was amusing but also irritating, but not unfitting with the plot. Also, the main characters in the nude most of the time wasn't interesting to me. Heinlein seems to beat you over the head with his opinions on societies and body shaming. But it's still pretty imaginative, which I appreciated.
Here on Amazon:
https://www.amazon.com/Number-Beast-R...
And here on half.com for 75 cents:
http://product.half.ebay.com/Number-o...