How do I decompose ctid into page and row numbers?

Question

Each row in a table has a system column ctid of type tid that represents the physical location of the row:

create table t(id serial);
insert into t default values;
insert into t default values;

select ctid
     , id
from t;

ctid  | id
:---- | -:
(0,1) |  1
(0,2) |  2

dbfiddle here

What's the best way of getting just the page number as from the ctid in the most appropriate type (eg integer, bigint or numeric(1000,0))?

The only way I can think of is very ugly.