git ls-tree –full-name HEAD

The 6 digits show the file mode using the classical UNIX notations. First two digits show file type, the third one is about set-uid/set-gid/sticky bits, and you know the last three.

Here is how man 2 stat documents it on my GNU/Linux system:

The following flags are defined for the st_mode field:

    S_IFMT     0170000   bit mask for the file type bit fields
    S_IFSOCK   0140000   socket
    S_IFLNK    0120000   symbolic link
    S_IFREG    0100000   regular file
    S_IFBLK    0060000   block device
    S_IFDIR    0040000   directory
    S_IFCHR    0020000   character device
    S_IFIFO    0010000   FIFO
    S_ISUID    0004000   set UID bit
    S_ISGID    0002000   set-group-ID bit (see below)
    S_ISVTX    0001000   sticky bit (see below)
    S_IRWXU    00700     mask for file owner permissions
    S_IRUSR    00400     owner has read permission
    S_IWUSR    00200     owner has write permission
    S_IXUSR    00100     owner has execute permission
    S_IRWXG    00070     mask for group permissions
    S_IRGRP    00040     group has read permission
    S_IWGRP    00020     group has write permission
    S_IXGRP    00010     group has execute permission
    S_IRWXO    00007     mask for permissions for others (not in group)
    S_IROTH    00004     others have read permission           
    S_IWOTH    00002     others have write permission
    S_IXOTH    00001     others have execute permission

32-bit mode, split into (high to low bits)

    4-bit object type
      valid values in binary are 1000 (regular file), 1010 (symbolic link)
      and 1110 (gitlink)

    3-bit unused

    9-bit unix permission. Only 0755 and 0644 are valid for regular files.
    Symbolic links and gitlinks have value 0 in this field.