Prince William and Kate Middleton get 13.5 million Instagram followers after son's birthday

Kate Middleton and Prince William's Instagram account has reached the 13.5 million mark.

The Duke and Duchess of Cambridge's official Instagram account garnered 13.5 million followers on Instagram after Kate Middleton shared some photos of the couple's son Prince Louis.

The Duchess posted pictures she recently took of her son's fourth birthday.

The first two photos posted before Louis' birthday were liked by nearly a million people on the photo and video sharing application, a milestone the couple's posts rarely reach.