Converting negative values from FROM_UNIXTIME

I have been trying to convert Date of birth from my DB into DATE FORMat but i am facing the problem of there are some negative values in DOB fields which when i check from online FROM_UNIXTIME calclator then it give different result and if i check it with FROM_UNIXTIME(-957632400) then it always returns NULL for negative values . KIndly let me know how can i get date format from such UNIX format like from -957632400