Python/Numpy: How large can a Numpy Unicode array be?

I found this line in https://numpy.org/doc/stable/reference/arrays.dtypes.html:

Total dtype itemsize is limited to ctypes.c_int.

Which for 32-bit signed integer would be 2,147,483,647. But practically, the byte size of the item is also limited, so divide by 4 (Unicode code point size) is 2147483647 // 4 or 536,870,911.

>>> import numpy as np
>>> np.array(['abcdef'],dtype='U536870911')
array(['abcdef'], dtype='<U536870911')
>>> np.array(['abcdef'],dtype='U536870911').itemsize
2147483644

Also:

dtype.itemsize

The element size of this data-type object.

For 18 of the 21 types this number is fixed by the data-type. For the flexible data-types, this number can be anything.