Either use

sudo cp -rp /home/folder /media/backup/folder

sudo cp -a /home/folder /media/backup/folder (UPDATE: use this one!!!preserves everything)

Or use:

 rsync -avz

-p     same as --preserve=mode,ownership,timestamps

 --preserve[=ATTR_LIST]
          preserve the specified attributes (default: mode,ownership,timestamps),
          if possible additional attributes: context, links, xattr, all

Source: https://unix.stackexchange.com/questions/43605/how-do-i-copy-a-folder-keeping-owners-and-permissions-intact