diff --git a/django/utils/numberformat.py b/django/utils/numberformat.py
index 488d6a77cd..35bbdd39e1 100644
--- a/django/utils/numberformat.py
+++ b/django/utils/numberformat.py
@@ -25,6 +25,8 @@ def format(
         module in locale.localeconv() LC_NUMERIC grouping (e.g. (3, 2, 0)).
     * thousand_sep: Thousand separator symbol (for example ",")
     """
+    if number == "":
+        return mark_safe(number)
     use_grouping = (
         use_l10n or (use_l10n is None and settings.USE_L10N)
     ) and settings.USE_THOUSAND_SEPARATOR
diff --git a/tests/utils_tests/test_numberformat.py b/tests/utils_tests/test_numberformat.py
index cec3e4c385..59fa421682 100644
--- a/tests/utils_tests/test_numberformat.py
+++ b/tests/utils_tests/test_numberformat.py
@@ -172,3 +172,6 @@ class TestNumberFormat(SimpleTestCase):
 
         price = EuroDecimal("1.23")
         self.assertEqual(nformat(price, ","), "€ 1,23")
+
+    def test_empty(self):
+        self.assertEqual(nformat("", "."), "")