diff --git a/core/src/main/java/org/apache/druid/java/util/common/parsers/TimestampParser.java b/core/src/main/java/org/apache/druid/java/util/common/parsers/TimestampParser.java
index ecd06f822f9..e5a9520c639 100644
--- a/core/src/main/java/org/apache/druid/java/util/common/parsers/TimestampParser.java
+++ b/core/src/main/java/org/apache/druid/java/util/common/parsers/TimestampParser.java
@@ -122,11 +122,12 @@ public class TimestampParser
   {
     final Function<String, DateTime> stringFun = createTimestampParser(format);
     final Function<Number, DateTime> numericFun = createNumericTimestampParser(format);
+    final boolean isNumericFormat = isNumericFormat(format);
 
     return o -> {
       Preconditions.checkNotNull(o, "null timestamp");
 
-      if (o instanceof Number) {
+      if (o instanceof Number && isNumericFormat) {
         return numericFun.apply((Number) o);
       } else {
         return stringFun.apply(o.toString());
@@ -134,6 +135,16 @@ public class TimestampParser
     };
   }
 
+  private static boolean isNumericFormat(String format)
+  {
+    return "auto".equalsIgnoreCase(format)
+           || "millis".equalsIgnoreCase(format)
+           || "posix".equalsIgnoreCase(format)
+           || "micro".equalsIgnoreCase(format)
+           || "nano".equalsIgnoreCase(format)
+           || "ruby".equalsIgnoreCase(format);
+  }
+
   private static DateTimeFormatter createAutoParser()
   {
     final DateTimeFormatter offsetElement = new DateTimeFormatterBuilder()
diff --git a/core/src/test/java/org/apache/druid/java/util/common/parsers/TimestampParserTest.java b/core/src/test/java/org/apache/druid/java/util/common/parsers/TimestampParserTest.java
index 9c0e66e10d2..a5622d51511 100644
--- a/core/src/test/java/org/apache/druid/java/util/common/parsers/TimestampParserTest.java
+++ b/core/src/test/java/org/apache/druid/java/util/common/parsers/TimestampParserTest.java
@@ -181,4 +181,48 @@ public class TimestampParserTest
                                    .getMillis()
     );
   }
+
+  @Test
+  public void testFormatsForNumberBasedTimestamp()
+  {
+    int yearMonthDate = 20200514;
+    DateTime expectedDt = DateTimes.of("2020-05-14T00:00:00.000Z");
+    Function<Object, DateTime> parser = TimestampParser.createObjectTimestampParser("yyyyMMdd");
+    Assert.assertEquals("Timestamp of format yyyyMMdd not parsed correctly",
+                        expectedDt, parser.apply(yearMonthDate));
+
+    int year = 2020;
+    expectedDt = DateTimes.of("2020-01-01T00:00:00.000Z");
+    parser = TimestampParser.createObjectTimestampParser("yyyy");
+    Assert.assertEquals("Timestamp of format yyyy not parsed correctly",
+                        expectedDt, parser.apply(year));
+
+    int yearMonth = 202010;
+    expectedDt = DateTimes.of("2020-10-01T00:00:00.000Z");
+    parser = TimestampParser.createObjectTimestampParser("yyyyMM");
+    Assert.assertEquals("Timestamp of format yyyy not parsed correctly",
+                        expectedDt, parser.apply(yearMonth));
+
+    // Friday, May 15, 2020 8:20:40 PM GMT
+    long millis = 1589574040000l;
+    expectedDt = DateTimes.of("2020-05-15T20:20:40.000Z");
+
+    parser = TimestampParser.createObjectTimestampParser("millis");
+    Assert.assertEquals("Timestamp of format millis not parsed correctly",
+                        expectedDt, parser.apply(millis));
+    parser = TimestampParser.createObjectTimestampParser("auto");
+    Assert.assertEquals("Timestamp of format auto not parsed correctly",
+                        expectedDt, parser.apply(millis));
+
+    int posix = 1589574040;
+    parser = TimestampParser.createObjectTimestampParser("posix");
+    Assert.assertEquals("Timestamp of format posix not parsed correctly",
+                        expectedDt, parser.apply(posix));
+
+    long micro = 1589574040000000l;
+    parser = TimestampParser.createObjectTimestampParser("micro");
+    Assert.assertEquals("Timestamp of format micro not parsed correctly",
+                        expectedDt, parser.apply(micro));
+
+  }
 }