Just a bit of curiousity, perhaps you can help me.
Mass of the 2004MN4 is given as 4.6e+10 kg
The online converter I used gave that as 39811 kilograms
That converted to 87,768.2311984 pounds, or almost 44 tons.
That seems like an awfully small number for an object with a diamter of .320 km (about a fifth of a mile), unless it's frozen gas.
Oh, wait, never mind... I found this page works better:
http://www.onlineconversion.com/weight_all.htm
46000000000 kilogram = 101,412,640,605.044 pounds
46000000000 kilogram = 50,706,320.3025218 tons [short]
Fifty million tons. Much better.
Glad to help.