5-digit-year in date export (52164-01-19 00:00:00+00)

Question

I received a data export from an unspecified source system, which includes dates in the format of:

1. 52164-01-19 00:00:00+00
2. 52992-08-12 04:29:36+00
3. 52838-10-19 04:08:32.999936+00
4. 54022-03-12 17:20:36.999936+00

I was told that the error is caused by a faulty conversion of unix to datetime (seconds and milliseconds).

We came up with a possible approach to refactor the date in python, by separating the year into a "normal" year (2164) and convert the rest into milliseconds.

import time
import math

d0 = '52164-01-19 00:00:00+00'
d0_y = 52164
multiplier = 5

# avg gregorian year in seconds
avg_greg = (365.2425 * 24 * 3600)

d1_modulus = 52164 % (1000 * multiplier)
d1_rest = d0_y - d1_modulus

# replace orginal year with modulus 
d1_time = time.strptime(str(d1_modulus) + '-10-19 04:08:32', '%Y-%m-%d %H:%M:%S')

#convert to milliseconds and add d1_rest in "seconds"
bigtime = time.mktime(d1_time) + (avg_greg * d1_rest) #in milliseconds
biggertime = bigtime / 1000 # in seconds
finaltime = time.ctime(biggertime)
# finaltime = 'Thu Mar 12 07:34:41 2020'
print(finaltime)

This code can break for different dates and result in multiplier/modulus combinations to create out of range values for time.mktime.

Can someone suggest an alternative or better approach to this?

Thanks in advance Gabe