Arindam, who was not in the initial probables list of Bengal squad batted for nearly five hours but didn't get enough support from the other end as only skipper Manoj Tiwary crossed the 20-run mark with Bengal being bowled out for 201 in 65.4 overs.
Mumbai scored 297 in their first essay with all-rounder Laxmi Ratan Shukla ending up with five-wicket haul.
Playing his 71st first-class match, the veteran opener Arindam faced 199 balls and hit 16 fours in the process. Left-arm spinner Ankit Chavan had the best figures of four for 61. Mumbai were six for no loss in the second essay.
With none of the other Bengal batsmen, barring skipper Tiwary giving Das meaningful support as the Mumbai bowlers struck to their task relentlessly on a wicket affording good carry for the new ball bowlers and copious turn for Chavan, in particular.
Das and Tiwary put on 72 runs in 120 balls and 101 minutes, but once this third wicket partnership was broken by Chavan who induced the rival skipper to drive on the up for a catch at mid-off, things went downhill for Bengal who lost their last five wickets for just 51 runs in 18.2 overs.
The only other batsman apart from Das and Tiwary to reach double figures was Subomoy Das (19). He was dropped at second slip off Chavan but failed to capitalise and fell to the next ball, caught at first slip to leave Bengal at 132 for 5.