Niven is an uncommonly occurring given name for males but a very prominent surname for both adults and children (#19272 out of 150436, Top 13%). (2000 U.S. Census). Shown below is the baby name popularity of Niven for boys.
So, what length is the right one for a book? The average nonfiction book, if such a thing exists, runs about 50,000 to 75,000 words, but this can vary depending upon category. Biographies, for example, can run 200,000 words.
Obviously, a prime determinant of book size is the word count. No matter how much you adjust the other variables, if the ms is only 50,000 words in length instead of 95,000, then you have a problem if the book was announced as being 288 pages in length but the most it can be stretched to is 160 pages.