One day, a person was in love. He wanted to find the person's phone number.
So they start up a conversation.
Person: What's your phone number, sweetheart?
Person's Love: I'm not going to give it that easily. If you replace the first digit of your phone number with the lowest odd digit, you'll get my number.
Person: And the 4-digit code before it?
Person's Love: You know, the product of the four digits in the code is actually the square root of my phone number.
Person: Hey, that's insufficient. I'm a plumber, not God.
Person's Love: But if I tell you the sum of digits of the code, I'd have told you too much.
Person: I love you, dear.
Person's Love: I love you too.
So what is the 4-digit code?