Get _m_s time format from milliseconds value

I could have any value in milliseconds like:

1040370

I must alert a specific converted time format : _m_s (ie:17m20s)

Here is how I do it:

function ms(a){ var m = a/1000/60, s = Math.floor(('0.'+(''+m).split('.')[1])*60); m = (''+m).split('.')[0]; alert(m+'m'+s+'s'); }  ms(1040370);

What do you think? Is it satisfactory or is there a better way to accomplish the same?