I recently sent some BTC from my Coinbase account to a Blockchain.info wallet, but the numbers I see are confusing. According to my Blockchain app, the transaction had a fee of .0001 BTC (for the miners, I get that). The BTC made it to my wallet, but the remaining .00120821 went somewhere else. Because of this, I wonder where did the .00120821 BTC get sent?
Unspent transaction output (UTXO) can only be spent in full, so if they don't match the amount you are trying to send exactly the rest will be sent back to yourself.
Therefore I assume that you had a single UTXO in your wallet. When it was spent, the remainder was sent to a change address in your own wallet.