Convert integer to hex-string with specific format

I am new to python and have following problem: I need to convert an integer to a hex string with 6 bytes.

e.g. 281473900746245 --> "\xFF\xFF\xBF\xDE\x16\x05"

The format of the hex-string is important. The length of the int value is variable.

The format '0xffffbf949309L' don't work for me. (I get this with hex(int-value))

My final solution (after some "playing") is:

def _tohex(self, int_value):
    data_ = format(int_value, 'x')

    result = data_.rjust(12, '0')
    hexed = unhexlify(result)

    return hexed

Thank you for all the help!