diff --git a/django/core/validators.py b/django/core/validators.py
index 5559bca28f7..6f4f5707656 100644
--- a/django/core/validators.py
+++ b/django/core/validators.py
@@ -40,6 +40,9 @@ class RegexValidator(object):
         if not self.regex.search(force_text(value)):
             raise ValidationError(self.message, code=self.code)
 
+    def __eq__(self, other):
+        return isinstance(other, RegexValidator) and (self.regex == other.regex) and (self.message == other.message) and (self.code == other.code)
+
 
 @deconstructible
 class URLValidator(RegexValidator):
@@ -139,6 +142,9 @@ class EmailValidator(object):
                 pass
             raise ValidationError(self.message, code=self.code)
 
+    def __eq__(self, other):
+        return isinstance(other, EmailValidator) and (self.domain_whitelist == other.domain_whitelist) and (self.message == other.message) and (self.code == other.code)
+
 validate_email = EmailValidator()
 
 slug_re = re.compile(r'^[-a-zA-Z0-9_]+$')
@@ -205,6 +211,9 @@ class BaseValidator(object):
         if self.compare(cleaned, self.limit_value):
             raise ValidationError(self.message, code=self.code, params=params)
 
+    def __eq__(self, other):
+        return isinstance(other, self.__class__) and (self.limit_value == other.limit_value) and (self.message == other.message) and (self.code == other.code)
+
 
 @deconstructible
 class MaxValueValidator(BaseValidator):
diff --git a/tests/validators/tests.py b/tests/validators/tests.py
index 23fa1e38303..ec91486658a 100644
--- a/tests/validators/tests.py
+++ b/tests/validators/tests.py
@@ -244,3 +244,59 @@ for validator, value, expected in TEST_DATA:
     name, method = create_simple_test_method(validator, expected, value, test_counter)
     setattr(TestSimpleValidators, name, method)
     test_counter += 1
+
+
+class TestValidatorEquality(TestCase):
+    """
+    Tests that validators have valid equality operators (#21638)
+    """
+
+    def test_regex_equality(self):
+        self.assertEqual(
+            RegexValidator(r'^(?:[a-z0-9\.\-]*)://'),
+            RegexValidator(r'^(?:[a-z0-9\.\-]*)://'),
+        )
+        self.assertNotEqual(
+            RegexValidator(r'^(?:[a-z0-9\.\-]*)://'),
+            RegexValidator(r'^(?:[0-9\.\-]*)://'),
+        )
+        self.assertEqual(
+            RegexValidator(r'^(?:[a-z0-9\.\-]*)://', "oh noes", "invalid"),
+            RegexValidator(r'^(?:[a-z0-9\.\-]*)://', "oh noes", "invalid"),
+        )
+        self.assertNotEqual(
+            RegexValidator(r'^(?:[a-z0-9\.\-]*)://', "oh", "invalid"),
+            RegexValidator(r'^(?:[a-z0-9\.\-]*)://', "oh noes", "invalid"),
+        )
+        self.assertNotEqual(
+            RegexValidator(r'^(?:[a-z0-9\.\-]*)://', "oh noes", "invalid"),
+            RegexValidator(r'^(?:[a-z0-9\.\-]*)://'),
+        )
+
+    def test_email_equality(self):
+        self.assertEqual(
+            EmailValidator(),
+            EmailValidator(),
+        )
+        self.assertNotEqual(
+            EmailValidator(message="BAD EMAIL"),
+            EmailValidator(),
+        )
+        self.assertEqual(
+            EmailValidator(message="BAD EMAIL", code="bad"),
+            EmailValidator(message="BAD EMAIL", code="bad"),
+        )
+
+    def test_basic_equality(self):
+        self.assertEqual(
+            MaxValueValidator(44),
+            MaxValueValidator(44),
+        )
+        self.assertNotEqual(
+            MaxValueValidator(44),
+            MinValueValidator(44),
+        )
+        self.assertNotEqual(
+            MinValueValidator(45),
+            MinValueValidator(11),
+        )