Saurav's Square #3Number Theory Level 4
Find the largest possible 7 digit number ABCDEFG such that
\[ (ABCDEFG)^2 = TUVWXYZABCDEFG. \].
Note: \(TUVWXYZABCDEFG\) is a 14 digit number where the variables \(A,B,C,D,E,F,G,T,U,V,W,X,Y,Z\) represent digits which need not be distinct from each other.