contacts2.db timestamp

Hello,

I have a contacts2.db which give me a timestamp of "1619907907543" in the table deleted_contracts. When I try to convert the timestamp with the Unix epoch time in millisec. then I get the 2021-05-02 which make no sence as that is aprox. 2 weeks after the phone was aquired.

I try to research it but I didn't find the information what kind of timestamp is used on Android phones. If that's important it's a Asus X00TDB (M1 Zenphone Max Pro)...

Thanks