I see that Turbo Tax is including the total amount that I got back from my annunity from Allianz. I understood only the interest earned was taxable. Do I have to pay tax on the $20000 that I put in on already taxed dollars?

Yes, you are correct that only the earnings on a prepaid Annuity are taxable.

Your Form 1099-R should have an amount in Box 1 (Distribution) and an amount in Box 2a (Taxable Amount).

If not, you may have an amount in Box 5 representing your Contribution to the annuity. 

If this is your first year receiving Annuity Payments, TurboTax will ask about the amount you contributed, plus some other questions, to determine the Taxable Amount. 

Depending on the type of annuity you have (deferred, non-qualified), some annuities distribute all the interest first, in which case the amount in Box 1 would be the taxable amount. 

Click this link for more info on Calculating the Taxable Portion of Annuity.