Delhi officially the National Capital Territory of Delhi, is a city and a union territory of India. It is bordered by Haryana on three sides and by Uttar Pradesh to the east. It is the most expansive city in India—about 1,484 square kilometres (573 sq mi). It has a population of about 25 million, making it the second most populous city after Mumbai and most populous urban agglomeration in India and 3rd largest urban area in the world. Urban expansion in Delhi has caused it to grow beyond the NCT to incorporate towns in neighbouring states. At its largest extent, there is a population of about 25 million residents as of 2014. According to data released by Oxford Economics, Delhi NCR urban agglomeration has replaced Mumbai Metropolitan Region urban agglomeration as the economic capital of India. However the comparison of the figures specific to the Metropolis of Delhi and Metropolis of Mumbai was not provided by this institution. These figures however did not match with those revealed by the reserve bank of India, The economic survey of India, The economic survey of Delhi and Maharashtra.