diff --git a/src/Rules/Functions/ParameterCastableToNumberRule.php b/src/Rules/Functions/ParameterCastableToNumberRule.php
index 3137688835..98584e45f3 100644
--- a/src/Rules/Functions/ParameterCastableToNumberRule.php
+++ b/src/Rules/Functions/ParameterCastableToNumberRule.php
@@ -11,6 +11,7 @@
 use PHPStan\Rules\ParameterCastableToStringCheck;
 use PHPStan\Rules\Rule;
 use PHPStan\Type\ErrorType;
+use PHPStan\Type\MixedType;
 use PHPStan\Type\Type;
 use function count;
 use function in_array;
@@ -69,7 +70,7 @@ public function processNode(Node $node, Scope $scope): array
 
 		$castFn = $this->phpVersion->supportsObjectsInArraySumProduct()
 			? static fn (Type $t) => $t->toNumber()
-			: static fn (Type $t) => !$t->isObject()->no() ? new ErrorType() : $t->toNumber();
+			: static fn (Type $t) => $t instanceof MixedType || $t->isObject()->no() ? $t->toNumber() : new ErrorType();
 
 		$error = $this->parameterCastableToStringCheck->checkParameter(
 			$origArgs[0],
diff --git a/src/Rules/ParameterCastableToStringCheck.php b/src/Rules/ParameterCastableToStringCheck.php
index 244cd1ba4f..28a24997fe 100644
--- a/src/Rules/ParameterCastableToStringCheck.php
+++ b/src/Rules/ParameterCastableToStringCheck.php
@@ -6,6 +6,7 @@
 use PHPStan\Analyser\ArgumentsNormalizer;
 use PHPStan\Analyser\Scope;
 use PHPStan\DependencyInjection\AutowiredService;
+use PHPStan\Node\Expr\TypeExpr;
 use PHPStan\Reflection\ParameterReflection;
 use PHPStan\Type\ErrorType;
 use PHPStan\Type\Type;
@@ -34,22 +35,31 @@ public function checkParameter(
 			return null;
 		}
 
-		$typeResult = $this->ruleLevelHelper->findTypeToCheck(
+		$arrayTypeResult = $this->ruleLevelHelper->findTypeToCheck(
 			$scope,
 			$parameter->value,
 			'',
-			static fn (Type $type): bool => $type->isArray()->yes() && !$castFn($type->getIterableValueType()) instanceof ErrorType,
+			static fn (Type $type): bool => $type->isArray()->yes(),
+		);
+
+		$arrayType = $arrayTypeResult->getType();
+		if (!$arrayType->isArray()->yes()) {
+			return null;
+		}
+
+		$typeResult = $this->ruleLevelHelper->findTypeToCheck(
+			$scope,
+			new TypeExpr($arrayType->getIterableValueType()),
+			'',
+			static fn (Type $type): bool => !$castFn($type) instanceof ErrorType,
 		);
 
-		if (
-			! $typeResult->getType()->isArray()->yes()
-			|| !$castFn($typeResult->getType()->getIterableValueType()) instanceof ErrorType
-		) {
+		if (!$castFn($typeResult->getType()) instanceof ErrorType) {
 			return null;
 		}
 
 		return RuleErrorBuilder::message(
-			sprintf($errorMessageTemplate, $parameterName, $functionName, $typeResult->getType()->describe(VerbosityLevel::typeOnly())),
+			sprintf($errorMessageTemplate, $parameterName, $functionName, $arrayTypeResult->getType()->describe(VerbosityLevel::typeOnly())),
 		)->identifier('argument.type')->build();
 	}
 
diff --git a/tests/PHPStan/Rules/Functions/ParameterCastableToNumberRuleTest.php b/tests/PHPStan/Rules/Functions/ParameterCastableToNumberRuleTest.php
index e4ebd5c149..48522ef8e4 100644
--- a/tests/PHPStan/Rules/Functions/ParameterCastableToNumberRuleTest.php
+++ b/tests/PHPStan/Rules/Functions/ParameterCastableToNumberRuleTest.php
@@ -18,12 +18,18 @@
 class ParameterCastableToNumberRuleTest extends RuleTestCase
 {
 
+	private bool $checkUnion = true;
+
+	private bool $checkExplicitMixed = true;
+
+	private bool $checkImplicitMixed = true;
+
 	protected function getRule(): Rule
 	{
 		$broker = self::createReflectionProvider();
 		return new ParameterCastableToNumberRule(
 			$broker,
-			new ParameterCastableToStringCheck(new RuleLevelHelper($broker, true, false, true, true, true, false, true)),
+			new ParameterCastableToStringCheck(new RuleLevelHelper($broker, true, false, $this->checkUnion, $this->checkExplicitMixed, $this->checkImplicitMixed, false, true)),
 			self::getContainer()->getByType(PhpVersion::class),
 		);
 	}
@@ -213,6 +219,39 @@ public function testBug13775Bis(): void
 		$this->analyse([__DIR__ . '/data/bug-13775-bis.php'], $this->hackPhp74ErrorMessages($errors));
 	}
 
+	public function testBug13775TerWithoutMixed(): void
+	{
+		$this->checkExplicitMixed = false;
+		$this->checkImplicitMixed = false;
+
+		$this->analyse([__DIR__ . '/data/bug-13775-ter.php'], $this->hackPhp74ErrorMessages([
+			[
+				'Parameter #1 $array of function array_sum expects an array of values castable to number, array<int, int|string> given.',
+				9,
+			],
+			[
+				'Parameter #1 $array of function array_product expects an array of values castable to number, array<int, int|string> given.',
+				10,
+			],
+		]));
+	}
+
+	public function testBug13775TerWithoutUnion(): void
+	{
+		$this->checkUnion = false;
+
+		$this->analyse([__DIR__ . '/data/bug-13775-ter.php'], $this->hackPhp74ErrorMessages([
+			[
+				'Parameter #1 $array of function array_sum expects an array of values castable to number, array<int, mixed> given.',
+				5,
+			],
+			[
+				'Parameter #1 $array of function array_product expects an array of values castable to number, array<int, mixed> given.',
+				6,
+			],
+		]));
+	}
+
 	public function testBug12146(): void
 	{
 		$this->analyse([__DIR__ . '/data/bug-12146.php'], $this->hackPhp74ErrorMessages([
diff --git a/tests/PHPStan/Rules/Functions/data/bug-13775-ter.php b/tests/PHPStan/Rules/Functions/data/bug-13775-ter.php
new file mode 100644
index 0000000000..acda0c1d71
--- /dev/null
+++ b/tests/PHPStan/Rules/Functions/data/bug-13775-ter.php
@@ -0,0 +1,10 @@
+<?php declare(strict_types = 1);
+
+/** @var mixed $a */
+$a = doFoo();
+echo array_sum([$a]) . "\n\n";
+echo array_product([$a]) . "\n\n";
+
+$b = rand(0, 1) ? 42 : '';
+echo array_sum([$b]) . "\n\n";
+echo array_product([$b]) . "\n\n";