How many CR 19 monsters are in the D&D 5e SRD?

1 CR 19 monsters appear in the SRD 5.2.1 — Balor.

How much XP is a CR 19 monster worth?

A CR 19 monster is worth 22,000 XP per the SRD's Experience Points by Challenge Rating table.

D&D 5e SRD · Challenge Rating

CR 19 monsters

1 monster at Challenge Rating 19 — worth 22,000 XP each (22,000 XP combined). Click into any of them to roll attacks, damage, and saves straight from the stat block.

Name	Type	Size	HP	AC
Balor	Fiend (Demon)	Huge	287	19

Stat blocks from the System Reference Document 5.2.1 © Wizards of the Coast LLC, used under the Creative Commons Attribution 4.0 license.