You should be inputting both a routing number and your account number in separate boxes. Each bank has different account number lengths, so I can't say if 16 digits is the right number for you. But, you should be able to see this information on a copy of any check from that account. It will be at the bottom - generally the routing number will come first and then your account number and then your check number (check sample image below). You DO NOT want to include the check number and 16 digits sounds like you may have included the check number. If your information is incorrect and the IRS is unable to deposit to your account, then they will convert your refund to a paper check and mail to the address on your return.
When I put in both the routing number and account number, turbo tax is saying my account number is wrong. I tried to recreate the direct deposit information and it's still coming back wrong.
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@SNODDY19531930 It would be a good idea to check with your bank and make sure you are using the correct routing and account numbers. You do not want to enter incorrect banking information into the software or your refund will be delayed--possibly for weeks.