For anyone interested, I did some quick math and it seems like it'd be about two tablespoons of hand sanitizer per person (500k people / 4000 litres).
This illustrates why naive number-formatting code that doesn’t take locale into account is wrong. The same number is written 20,000,000 in the US, 20.000.000 in most of continental Europe, and 2,00,00,000 in India.
I formerly worked on a now-defunct Indian e-commerce site, and many of my fellow developers (and me) were Westerners with little exposure to Indian culture. It was relatively common for new employees to file a “bug” pointing out that the site was formatting large numbers “wrong”, not realizing that it was correct for India.
Google states that for: "(4000 litres / 500000) in tablespoons": the result is "0.541024363 US tablespoons"