total coin supply 24993009

if you need 656667.67 for masternode, you will have only maximum 38 masternodes
for better security and right now affordable for anyone -  you should have more masternodes!

DRK is 1000 coins for master node and ~5 million coins exist - possible 5000 masternodes..

with that calculation - you need to enable masternode from minimum 5000 coins.