N is natural number greater than 1. When 1 is add to N, the result is a multiple of 2; when 2 is add to N, the result is a multiple of 3; when 3 is add to N, the result is a multiple of 4; when 4 is add to N, the result is a multiple of 5; when 5 is add to N, the result is a multiple of 6; when 6 is add to N, the result is a multiple of 7. Find the smallest value of N.