Transact SQL :: Nvarchar (max) Not Storing Whole Data

select name from sampletext where id=1

Value under the column name where id=1 is:- uhfhdajkfahgfiasfhgafahsfiahfiahfsai......(upto 600000 characters)

The value under the name column is more than 600000 characters. When i am using the following logic it is storing upto 72000 characters, not reading the whole value under the 'name' column.

Code:-
declare @s1 nvarchar(max)
declare @substr nvarchar(max)
set @s1 = (select name from sampletext where id=1)declare @i int
declare @i int
DECLARE @j int

[Code] .....

Is there a way to get whole characters under a column instead of storing limited characters?