Forum:Need help sourcing Isildur's birth year to texts

Hello, you folks are kind of my last hope. You have a birth year for Isildur here. I need to source it to a text. I'm writing a long blog series on encounters with the ring, and I am trying to deal with Isildur. Can't find the birth year anywhere. If this has already been discussed to death, I'll be happy with a link to the thread. Thanks!