Any number to the 6th power will be both a squared number and a cubed number. The first 10 such numbers are: 1 64 729 4096 15625 46656 117649 262144 531441 1000000
No.I think you mean "Is the number 2 a cubic number?" meaning, "Is there any number cubed that will equal 2?".The first cubic number is 1 (13), then 8 (23). So the cubic numbers skip straight past...
If you mean the sum of two cubed numbers then the answer is simply 'none' with the trivial exception of all of them being 0. For more info check out "Fermat's last theorem".