How to convert hubspot timestamps to meaningful datetime?



We're importing the hubspot DB to our BigQuery.

On the property I see strange value such as: 1525801948522, 1525774682022.

I could not figure out what timestamp they represent? (These are not Unix timestamps)
I want to convert them to a datetime which I could actually use SQL queries on.

Does anyone have an idea?

Many thanks,


Replying to myself.
It is unix time - just need to divide by 1000.