Does this happen only with that mic or with all mics? Does this happen when you switch on phantom power without a mic connected?
If your answer is yes on the second question there could be a faulty condensor inside your interface which should filter out the DC voltage of the phantom power but it can't
You said : if i touch the xlr port..... What part of the connector do you touch and is the mic plugged in? If mic is plugged in and you touch the casing of the xlr port and the hum dissappear it cod be a ground loop / faulty ground connection inside your microphone....
Do you have other information for us so we can explore your problem together..