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.
I believe that the average words per page for a paperback book is 350 words. So, to figure out how many pages your manuscript would be as a paperback book, you would have to divide the word count of your novel by 350. Here is an example.