import struct


def signed_int_to_unsigned_hex(signed_int: int) -> str:
    """Converts a signed int value to a 64-bit hex string.

    Examples:
        1662740067609015813  => '17133d482ba4f605'
        -5270423489115668655 => 'b6dbb1c2b362bf51'

    :param signed_int: an int to convert
    :returns: unsigned hex string
    """
    hex_string = hex(struct.unpack('Q', struct.pack('q', signed_int))[0])[2:]
    if hex_string.endswith('L'):
        return hex_string[:-1]
    return hex_string