diff --git a/django/utils/numberformat.py b/django/utils/numberformat.py
index 35bbdd39e1..6e3628ff91 100644
--- a/django/utils/numberformat.py
+++ b/django/utils/numberformat.py
@@ -25,7 +25,7 @@ def format(
         module in locale.localeconv() LC_NUMERIC grouping (e.g. (3, 2, 0)).
     * thousand_sep: Thousand separator symbol (for example ",")
     """
-    if number == "":
+    if number is None or number == "":
         return mark_safe(number)
     use_grouping = (
         use_l10n or (use_l10n is None and settings.USE_L10N)
diff --git a/tests/utils_tests/test_numberformat.py b/tests/utils_tests/test_numberformat.py
index 59fa421682..3c7620c744 100644
--- a/tests/utils_tests/test_numberformat.py
+++ b/tests/utils_tests/test_numberformat.py
@@ -175,3 +175,4 @@ class TestNumberFormat(SimpleTestCase):
 
     def test_empty(self):
         self.assertEqual(nformat("", "."), "")
+        self.assertEqual(nformat(None, "."), "None")