You'll need to add 01Jan1970 to each of those.
You can use 01Jan1970 as an unquoted constant to do that.
For example:
today70=1583246337; //03Mar2020 in seconds since 01Jan1970;
today_jmp=today70 + 01Jan1970; //add number of seconds from 01Jan1904
format(today_jmp, "mm/dd/yyyy");
Results:
/*:
"03/03/2020"
Note: you can use any date, not just 01Jan1970, as a constant like that.
-Jeff