The parameters have changed and publishers are now looking for longer novels -- say, 100K to 300K words. A lot of that is achieved by padding.
A couple of years ago the Booker Prize (for novels) was won by a novel of only 65,000 words. Many of the other (outraged) contestants claimed that it was only a novella.
My own novel is only about 65K and I'd call it a short novel, though as recently as 1990 it would have been the normal length.
I think it takes as many words, and chapters, as are necessary to tell the story. Let the pedants argue about whether it's a genuine novel. The proof of the novel is in the reading.