Python power operator in a loop: strange output values after a certain element

I identified a strange behaviour of the ** operator. Here is the code:

import numpy as np

n = np.arange(0,20)

print(np.c_[n,10 **n])

I obtain the following output:

array([[                   0,                    1],
       [                   1,                   10],
       [                   2,                  100],
       [                   3,                 1000],
       [                   4,                10000],
       [                   5,               100000],
       [                   6,              1000000],
       [                   7,             10000000],
       [                   8,            100000000],
       [                   9,           1000000000],
       [                  10,          10000000000],
       [                  11,         100000000000],
       [                  12,        1000000000000],
       [                  13,       10000000000000],
       [                  14,      100000000000000],
       [                  15,     1000000000000000],
       [                  16,    10000000000000000],
       [                  17,   100000000000000000],
       [                  18,  1000000000000000000],
       [                  19, -8446744073709551616]])

I do not understand the reason of the out for n=19.