The first draft shared with my publisher was 39,000 words,
Here (with 2 Years of Exhausting Photographic Detail) Is How To Write A Book
Ryan Holiday

I have never understood the reason to measure a book, rather than for writing an article, by the number of words rather than the number of pages. I can’t imagine that there are folks about saying something like ‘Oh honey, while you’re at the bookstore pick me up a 40,000 word novel will you dear.’ What’s the point?