Transaction Error invalid BigNumber string (argument="value", value="1.2e+21", code=INVALID_ARGUMENT, version=bignumber/5.5.0)

Question

Hello i have a problem on string bignumber when transfering morthan 1000BUSD this is my transfer code,, i dont know what problem i hope someone help me thanks

const transfer = async (fromAddress, toAddress, amount, callback) => {
    if (connected === true) {
      if (chainId !== config.chainId) {
        //56   97
        alert("Please select Biance Smart Chain network!");
        return;
      }
      setIsLoading(true);

      try {
        let tx = await Contract.methods
          .transfer(toAddress, (amount * Math.pow(10, 18)).toString())
          .send({ from: fromAddress, to: toAddress });

       // console.log(tx.events.Transfer.id);
        setIsLoading(false);
        success_transfer();
        callback();
      } catch (error) {
        setIsLoading(false);
        //console.log(error.message);
        error_transfer(error.message);
      }
    } else {
      alert("Please connect to the wallet");
      ConnectWallet();
    }
  };