Exporting a datatable to csv format

Question

Hi,

     I'm importing a datatable into a csv format ,and i am giving the phonenumber as 20000000000000000090456527365 and this value after exporting to csv format in the excel file it shows that value as 2E+28.But i want that number as 20000000000000000090456527365 in the excel sheet.
please help me to overcome this problem.

Thanks in advance

2E+28

2E+28