In order to understand mathematics you must wade through a lot of language. Mathematicians invent language in order to understand their linguistic constructions which leads to more questions, more explanations, more constructions. Formally, this has been going on for at least 3,000 years. In order to write a story that allows mathematics to take center stage you need to avoid actual mathematics if you wish to have any room left for a story line. Unfortunately, when you eliminate the actual mathematics, you cannot allow your readers to directly experience the actual feelings that take place when working on mathematics.
Most people understand numbers intuitively.
That is why number theory is a good choice for this story. But the author is left blowing real hard into a balloon with a big hole, hoping that it inflates a little bit for a few instants so the reader can get a glimmer of what is really going on. I think this leaves most readers a little cold. Readers without a mathematical background are left groping in the dark and those of us with one wish there was more mathematics in the story. The other thing is that math must be done in a very controlled emotional environment, something akin to a meditative state.