The purchase cost of a heat exchanger of 20 m$^{2}$ area was Rs 500000 in 2006. What will be the estimated cost (in Rs to the nearest integer) of a similar heat exchanger of 50 m$^{2}$ area in the year 2013? Assume the six-tenths factor rule for scaling and the cost index for 2006 as 430.2. The projected cost index for the year 2013is 512.6. $\_\_\_\_\_\_\_\_$