diff --git a/pandas/core/indexes/base.py b/pandas/core/indexes/base.py
index c002832cd89bb..693b4827acf19 100644
--- a/pandas/core/indexes/base.py
+++ b/pandas/core/indexes/base.py
@@ -4896,6 +4896,11 @@ def _concat(self, to_concat: list[Index], name: Hashable) -> Index:
         to_concat_vals = [x._values for x in to_concat]
 
         result = concat_compat(to_concat_vals)
+
+        is_numeric = result.dtype.kind in ["i", "u", "f"]
+        if self._is_backward_compat_public_numeric_index and is_numeric:
+            return type(self)._simple_new(result, name=name)
+
         return Index._with_infer(result, name=name)
 
     @final
diff --git a/pandas/tests/indexes/common.py b/pandas/tests/indexes/common.py
index 7e43664c6b3de..38127a0e255bd 100644
--- a/pandas/tests/indexes/common.py
+++ b/pandas/tests/indexes/common.py
@@ -760,6 +760,19 @@ def test_index_groupby(self, simple_index):
         expected = {ex_keys[0]: idx[[0, 4]], ex_keys[1]: idx[[1, 3]]}
         tm.assert_dict_equal(idx.groupby(to_groupby), expected)
 
+    def test_append_preserves_dtype(self, simple_index):
+        # In particular NumericIndex with dtype float32
+        index = simple_index
+        N = len(index)
+
+        result = index.append(index)
+        assert result.dtype == index.dtype
+        tm.assert_index_equal(result[:N], index, check_exact=True)
+        tm.assert_index_equal(result[N:], index, check_exact=True)
+
+        alt = index.take(list(range(N)) * 2)
+        tm.assert_index_equal(result, alt, check_exact=True)
+
 
 class NumericBase(Base):
     """