According to the fifth national census (March 2011) taken by Bangladesh Bureau of Statistics (BBS) the population of Bangladesh stands at 142.319 million. The ratio between males and females are almost equal comprising 71.255 million and 71.064 million males and females respectively.
The population has been growing at the rate of 1.34 percent annually, 14.4 percent growth of population since last census (2001, 124.355 million. The number of households stands at 32.068 million, with average 4.4 people constituting one household. With 8,111 people living every square kilometre, Dhaka is the most densely-populated district; 964 people live in every square kilometer of the country in average.
Now this statistics will also surprise you. The total number of Mobile Phone Active Subscribers has reached 76.434 million at the end of June 201 which accounts to roughly 53.71% of population.
Here is a detailed analysis what these number means (in Bangla). If the current mobile phone growth rate continues (6 million in past six months) then the number could reach 82.5 millions (57.70% reach) by the end of this year. That isn't bad for a developing country. Just imagine how fast the mobile internet users can grow (currently ca 10 million).