How much interest amount i would be paying in 20 years, if i am acquiring loan of Rs.16,82,000 @ 8.5%?

When you applied they must have intimated of the current(8.5%) EMI rate. Anyways, for 8.5% pa and 20 yrs. tenure , the EMI comes aprroximately Rs. 1000 per 1,00,000 of loan amount. so in 20years a debtor pays 2, 40,000 in total to the bank i. e. 1,40, 000 Rs. interest on 1,00,000 loan amount. So, for Rs. 16,80,000 you will be paying 1,40,000 x 16.8 = 23,52, 000 Rs. as interest.