These are Yoldal brand superbright warm white LEDs, part number YZ-WS5S20N. They have an intensity rating of 9200mcd at a beam angle of 20 degrees. Total luminous flux is listed at 2.4 lumens!
These LEDs are made in Taiwan (by Yoldal), not mainland China, so their quality is much better than most 5mm white LEDs.
Datasheet is here.