For your eBook-only project, you can choose as few as 2 pages for your book.
For your printed book, you need at least 24 pages. We require a minimum of 24 pages in order to bind the book. This applies to both soft cover and hard cover books.
If you are close to 24 pages, you may consider adding more content, such as a Title page, Copyright page, and/or Dedication page. Children's books can often gain pages by adding some extra art or colored/patterned pages at the front and back of the book.
Another option is to simply add blank pages to the back of your book. For example, if you are at 21 pages, your printed book could have a blank page 22, 23 and 24 added to it.