TITLE: prove that $10200300040000100004000300201$ is not perfect square
QUESTION [21 upvotes]: How can I prove that $ 10200300040000100004000300201$ is not a perfect square ? This number is divisible with $3$ only one time. Is it a good reason and it is enough ? 
thanks :)

REPLY [2 votes]: The digital root of a square is $1, 4, 7$, or $9$. Yours is $3$...