Magento: How do I get categories for a product in Magento?

List the categories a product belongs to

$product = Mage::getModel('catalog/product')->load($productId);

$cats = $product->getCategoryIds();
foreach ($cats as $category_id) {
    $_cat = Mage::getModel('catalog/category')->load($category_id) ;
    echo $_cat->getName();
}