719

This number is a prime.

The first occurrence of three consecutive multidigit prime values y₀ of the fundamental solution pair (x₀, y₀) to Pellian x² - Dy² = 1 corresponding to prime values D as well: 516960² - 516959*719² = 1 ; 528528² - 528527*727² = 1 ; 537288² - 537287*733² = 1. [Beedassy]