Enter numbers into the grid that comply with the following clues:
Across
2. The sum of the digits in 2 down (2)
4. A prime number (2)
5. 1 down + 2 across + 3 down (3)
Down
1. A palindromic number (2)
2. 9 x 1 down (3)
3. 4 across squared (3)