Field types

I'm new to PostgreSQL and after a week of going through the documentation
and looking at the database types i want to know if there is an Integer type
on
64 bits. Something like long long integer type. I found Int8 wich is
supposed
to be an integer on 8 bytes but it looks like a double precision to me.

I tried inserting this in an int8 integer: 9223372036854775807 and failed.
Since
it is my first contact with this rdbms i think i'm looking at the wrong
field type,
yet again i find no other 18 digits integer (64 bit integer is 19 digits
wide) to hold
a full longlonginteger (i also tried only 18 digits without any success).

Any hint as of where to look for would be very apreciated.
TIA

Best regards,
Aplication Developer
Pirtea Calin Iancu
S.C. SoftScape S.R.L.
pcalin(at)rdsor(dot)ro