Splitting variable to two variables

I need to split 16 byte variable to two variables. What is the best way to do it?

I need to convert for example variable 1000000000000001 to variables 10000000 and 00000001.

Do you really mean a 16-byte variable? Your example is 16 digits but that wouldn't need 16 bytes.
What sort of data would be in such a variable? Maybe an array would be easier to deal with.

quilkin:
Your example is 16 digits but that wouldn't need 16 bytes.

It's also 16 binary digits, aka bits

Pezq:
I need to split 16 byte variable to two variables.

The OP said byte, although I guess bit was intended. I was just checking.