What is significant about the chapter numbers in the novel 'The Curious Incident of the Dog in the Night-Time'?

The Curious Incident of the Dog in the Night-Time is a 2003 mystery novel by British writer Mark Haddon. Its title quotes the fictional detective Sherlock Holmes in Arthur Conan Doyle's 1892 short story "Silver Blaze". Haddon and The Curious Incident won the Whitbread Book Awards for Best Novel and Book of the Year, the Commonwealth Writers' Prize for Best First Book, and the Guardian Children's Fiction Prize. Unusually, it was published simultaneously in separate editions for adults and children.

The book uses prime numbers to number the chapters, rather than the conventional successive numbers.

The novel is narrated in the first-person perspective by Christopher John Francis Boone, a 15-year-old boy who describes himself as "a mathematician with some behavioural difficulties" living in Swindon, Wiltshire. Although Christopher's condition is not stated, the book's blurb refers to Asperger syndrome, high-functioning autism, or savant syndrome. In July 2009, Haddon wrote on his blog that "Curious Incident is not a book about Asperger's....if anything it's a novel about difference, about being an outsider, about seeing the world in a surprising and revealing way. The book is not specifically about any specific disorder," and that he, Haddon, is not an expert on autism spectrum disorder or Asperger syndrome.