SAS date and datetime values are stored as numeric and a length of 8 is correct as well. The number you see looks like a SAS datetime value which is nothing else than the count of seconds since 1/1/1960.
The only thing you need to do is apply a SAS format to the numerical column so your SAS datetime value becomes human readable. Here the docu explaining this much better than I can.
data test;
dttm=1878249600;
dttm2=dttm;
dttm3=dttm;
format dttm2 datetime21. dttm3 B8601DN10.;
output;
stop;
run;
proc print data=test;
run;