According to the studies by CIA world Factbook, and their 2018 estimates, Mandarin Chinese has the highest number of native speakers, having 941 million equal to (12.3%) of the world population. Spanish comes next with 486 million (6.0%) of the population and then English and Arabic with 5.1% each. Hindi (3.5%), Bengali (3.3%), Portuguese (3.0%), Russian (2.1%), Japanese (1.7%), Western Punjabi (1.3%) and Javanese (1.1) comes in the decreasing order.
All the above languages are spoken by more than 60 million people each. There are other languages as well spoken in the same numbers and above like French, Turkish, Korean, Urdu, Vietnamese, etc. but not fully as their fist language.
A lot of interesting acts are given in the following link:
https://en.wikipedia.org/wiki/List_of_languages_by_number_of_native_speakers
