diff --git a/pandas/core/frame.py b/pandas/core/frame.py
index 0437c479c9d81..dccc840f5affd 100644
--- a/pandas/core/frame.py
+++ b/pandas/core/frame.py
@@ -2231,7 +2231,7 @@ def _sizeof_fmt(num, size_qualifier):
             # returns size in human readable format
             for x in ['bytes', 'KB', 'MB', 'GB', 'TB']:
                 if num < 1024.0:
-                    return ("{num:3.1f}{size_q}"
+                    return ("{num:3.1f}{size_q} "
                             "{x}".format(num=num, size_q=size_qualifier, x=x))
                 num /= 1024.0
             return "{num:3.1f}{size_q} {pb}".format(num=num,
diff --git a/pandas/tests/frame/test_repr_info.py b/pandas/tests/frame/test_repr_info.py
index 8fc6fef11798a..668613c494a47 100644
--- a/pandas/tests/frame/test_repr_info.py
+++ b/pandas/tests/frame/test_repr_info.py
@@ -5,6 +5,7 @@
 from datetime import datetime, timedelta
 import re
 import sys
+import textwrap
 
 from numpy import nan
 import numpy as np
@@ -204,6 +205,25 @@ def test_info(self):
         frame.info()
         frame.info(verbose=False)
 
+    def test_info_memory(self):
+        # https://github.com/pandas-dev/pandas/issues/21056
+        df = pd.DataFrame({'a': pd.Series([1, 2], dtype='i8')})
+        buf = StringIO()
+        df.info(buf=buf)
+        result = buf.getvalue()
+        bytes = float(df.memory_usage().sum())
+
+        expected = textwrap.dedent("""\
+        <class 'pandas.core.frame.DataFrame'>
+        RangeIndex: 2 entries, 0 to 1
+        Data columns (total 1 columns):
+        a    2 non-null int64
+        dtypes: int64(1)
+        memory usage: {} bytes
+        """.format(bytes))
+
+        assert result == expected
+
     def test_info_wide(self):
         from pandas import set_option, reset_option
         io = StringIO()