Puzzle No. 46 - Number of the day!

Assume the number as ABCD

1. First 2 digits and last 2 digits are successive multiples
2. If you add first 2 digits with last 2 digits you get a three digit number which has a special attribute (what's special about this number)
3. If you reverse the 4 digit number (DCBA) and add DC + BA you get a perfect square
4. DC and BA are even multiples of two prime numbers

Question Number 45 - Find the perfect square

Find the 4 digit number
- Its a perfect square
- Remove the 2nd digit an it is still a perfect square
- Add 3 to the second digit and again you get a perfect square
- Replace the first 2 digits by one of its factor and you get a perfect square again1

Mathematics question - Number 44

A reasonably simple Mathematics question before the week-end passes by...
Two Men are walking down a park and notices a car with 4 digit registration number
1st guy remembers the first 2 digits and 2nd one takes up the last two digits
1st Guy: If I add the first digit of your number to my 2 digit number, I get a perfect square
2nd Guy: If I subtract the second digit of your number from my 2 digit number, I get a perfect square as well
1st Guy exclaims... If we add both our 2 digit numbers, it is also a perfect square!
2nd Guy's turn now... The entire 4 digit number is a perfect square as well!
What's the 4 digit number they are referring to?