You are adding the number of bytes, too
TrafficStats.getTotalRxBytes() + TrafficStats.getTotalTxBytes() / 1000000
So you are writting two numbers together, without spaces or any separators in between (first number of bytes, then number of MB).
Use brackets to aggrupate the operations
(TrafficStats.getTotalRxBytes() + TrafficStats.getTotalTxBytes()) / 1000000