Arduino-Long-Int to Binary-String

Hello everyone,

is there anyway to convert an Arduino-Long to a Binary-String? I found the function "itoa()" but the maximum convertable value is 65535 which is equal to "1111111111111111". But I need bigger values for example the biggest value for a long: 2147483647. I want to convert this to a Binary-String in form of this:
"1111111111111111111111111111111".

Does anyone know how?
Thanks.

char *ltoa(long N, char *str, int base);

Thanks. I did not know there is a ltoa() Function