SQL Formatting: Add Space within query result
You can do this several ways. I'm assuming this is stored as a number and not a string, and I'm using RTRIM to prevent invalid datatype errors.

DECLARE @i BIGINT = 1234567891234567891

SELECT LEFT(@i, 4) + ' ' + RIGHT(@i, LEN(@i) -4) AS lefty_righty

SELECT SUBSTRING(RTRIM(@i), 0, 5) + ' ' + SUBSTRING(RTRIM(@i), 5, LEN(@i)) AS substrings

SELECT STUFF(RTRIM(@i), 5, 0, ' ') AS stuffy