std::unordered_map::bucket_count

From cppreference.com

size_type bucket_count() const;
(since C++11)

Returns the number of buckets in the container.

Parameters

(none)

Return value

The number of buckets in the container.

Complexity

Constant.

See also

returns the number of elements in specific bucket
(public member function)
returns the maximum number of buckets
(public member function)