Since there are only five different digits, a 6-digit number can only be generated if a digit can be repeated. If digits can be repeated, the smallest 6-digit number is 111111.
The smallest number with no digits repeated would either be zero or one, depending on the set of numbers you want to choose from.
The first digit would have to be 1, the remaining digits, zero.
1000000000 or, if negative numbers are permitted, then -9999999999
The largest ten digit number with no repeated digits is '9876543210'.