Across

Down

 1. a square number

 1. reads the same both ways (palindrome)

 4. a square number

 2. square root of 28 across

 5. a square number

 3. sum of 17 across and 21 across

 8. the digits of this number add to 35

 4. digits add to 19

 11. square root of 39 across

 5. digits add to 26

 13. a square number

 6. sum of 14 across and 33 across

 14. a square number

 7. a cube number

 15. square of 36 across

 9. a cube number

 17. square of half 11 across

 10. a square number

 18. three same digits

 12. digits sum to 30

 19. product of 4 across and 33 across

 14. all digits are the same

 21. a square number

 16. sum of digits is 2 down

 22. five times 5 across

 18. all digits the same, except the for the first digit, which is 1

 23. all digits same, except central digit

 20. sum of 17 across and 27 across

 25. square of 2 down

 21. a multiple of 19

 27. see 20 down

 22. a square number

 28. a fourth power

 24. a square number

 29. sum of 18 across and 31 across

 26. square of 18 across

 31. a triangular number

 28. a fourth power of 4 across

 33. one more than 4 times 36 across

 29. two times 15 across

 34. the digits add to 18, and the three middle numbers are 3

 30. a triangular number

 36. an odd number

 32. digits add to 20, last digit is 8

 37. all digits are even except one, sum of digits is 29

 34. six times 21 across

 39. a fourth power

 35. a cube number

 40. a cube number

 37. a square number

 41. two times a square number

 38. a cube number