As of my last knowledge update in September 2021, the population of Adana was estimated to be around 2.2 million, making it the fifth most populous city in Turkey.1
References
1Çuhadar M, Çeli Çaylak P, Topsakal Y. A quantitative study to determine the motivations, perceptions, and behaviours of participants in the adana orange blossom carnival. International Journal of Contemporary Economics and Administrative Sciences. Published online 2023-12. doi:10.5281/ZENODO.10475708