how can I handle large numbers in Python?

Question

I would like to make a Python code for Paillier Encryption and I have made the code, which works well with small number e.g. 32bit. But I would like to make it work even though the number is very very large (till 1024 bit)

So I tried this code which p,q (random choosed Primenumber) here is the code

from random import randint
import libnum
import sys
import random

import numpy as np ## in order to save the time

def gcd(a,b):
    """Compute the greatest common divisor of a and b"""
    while b > 0:
        a, b = b, a % b
    return a
    
def lcm(a, b):
    """Compute the lowest common multiple of a and b"""
    return a * b // gcd(a, b)

def L(x,n):
    return ((x-1)//n)


#%% Key generation (Schlüsselerzeugung)
find_primenumber=2**513
# um die 
a = [False,False] + [True]*(find_primenumber-1)
primes=[]
# Algorism of eratosthenes
for i in range(2,find_primenumber+1):
  if a[i]:
    primes.append(i)
    for j in range(2*i, find_primenumber+1, i):
        a[j] = False

# print('the choosable prime numbers are : ',primes)


p= random.sample(primes, 2)[0]
q=random.sample(primes, 2)[1] ## two prime numbers are randomly choosed

# öffentliche Schlüssel public key (n,g)
n = p*q 
# um Schlüssellänge zu vergrößen, muss n noch größer werden
# sys.getsizeof(n)
# in case n = 2499995600000711 size of n is 32
g = n+1 #Pick a random integer g in the set Z∗n2 (integers between 1 and n2)
gLambda = lcm(p-1,q-1) ## in Matlab cipher = lambda

m= str(input('Enter plaintext :')) #must be string type
m= list(m)
m_list=[]

for i in range(0,len(m)):
    m_list.append(ord(m[i])) ## must be saved as a list

m_1=np.array(m_list)
if (len(sys.argv)>1):
    m=int(sys.argv[1])

if (len(sys.argv)>2):
    p=int(sys.argv[2])

if (len(sys.argv)>3):
    q=int(sys.argv[3])

if (p==q):
    print("P and Q cannot be the same")
    sys.exit()
l = (pow(g, gLambda, n*n)-1)//n
gMu = libnum.invmod(l, n)    


if (gcd(g,n*n)==1):
    print("g is relatively prime to n*n")
else:
    print("WARNING: g is NOT relatively prime to n*n. Will not work!!!")
# geheime Schlüssel (private key)
r=[]
for i in range(0,len(m)):
    r.append(randint(1,n))

#%% Encryption
# changed: pow(a,b,n) for modular exponentiation a^b mod n
# --> much faster than the standard pow()
# shortened the code
c=[]
for i in range(0,len(m)):
    k1 = pow(g, m_list[i], n**2)
    k2 = pow(r[i], n, n**2)
    c.append((k1*k2)%(n**2));

but I get this answer from the Console

OverflowError: cannot fit 'int' into an index-sized integer

How can I fix it and make it work even the find_primenumber is large enough?