Problem

intword() decides whether rounding pushed a value up into the next magnitude
with:

if not largest_ordinal and rounded_value * power == powers[ordinal + 1]:

For values above ~10**22, rounded_value * power is evaluated in floating
point and no longer equals the exact powers[ordinal + 1], so the carry is
skipped and the number is rendered against the lower magnitude:

>>> import humanize
>>> humanize.intword(10**24 - 1)
'1000.0 sextillion'      # expected '1.0 septillion'
>>> humanize.intword(10**27 - 1)
'1000.0 septillion'      # expected '1.0 octillion'

The same happens at 10**30 and 10**33.

Fix

Compare rounded_value against the exact integer ratio
powers[ordinal + 1] // power, keeping the check in exact integer terms rather
than relying on a large float product. This mirrors the recently fixed carry
handling in metric() (#328) and naturalsize() (#329).

Tests

test_intword_rounding_rollover asserts the correct roll-over across every
affected magnitude (10**24/27/30/33 - 1), plus a couple of just-below cases
that must not roll over, guarding both directions.

pytest → 716 passed. ruff check / ruff format --check clean.