I am trying to find the total wattage for this long mercury UV industrial curing lamp I have in my collection...
All the info I have is that it is 135cm long, 20mm in diameter and has an arc length of 125-130cm.

Its made by Alpha-Cure in the UK and the only number it has etched on is "F2460364".

Previous research shows it could be the AC-0209, which is a 19.7kW/19.700W lamp.

Meaning, if my lamp really is this model, it is the most powerful HID lamp I own.

20.000W is an incredible amount of power for such a small lamp.

Can anyone confirm it?

Sounds like a medium pressure lamp? I wouldn't doubt 20kW cause something as small as this can take 12kW it's quite realistic.