There are a few different ways:
select 1637804567::varchar::date as date;
+------------+
| DATE |
|------------|
| 2021-11-25 |
+------------+
select to_date(1637804567::varchar) as date;
+------------+
| DATE |
|------------|
| 2021-11-25 |
+------------+
TO_DATE or CASTING will require the value to be string, so you need to convert the integer to string first before converting to date.
For your example, it will be like below in Snowflake:
select dateadd(ms, 54600*1000, to_date(1637804567::varchar)) as date;
+-------------------------------+
| DATE |
|-------------------------------|
| 2021-11-25 15:10:00.000000000 |
+-------------------------------+