There is no magic number. The ideal length is whatever it takes to answer the user's question completely and usefully, without padding. That said, consistent studies show that articles between 1,500 and 3,000 words tend to rank better for competitive terms.
What matters more than length is topical coverage. If the article covers every relevant aspect of the topic, with depth and a clear structure, it tends to perform well whether it has 800 or 4,000 words. Short articles can work for simple questions. Long articles are necessary for complex topics.
A common mistake is artificially inflating content to hit an arbitrary word count. That results in articles with repetitive paragraphs and irrelevant sections that hurt the reader experience and engagement signals. Write what is needed, cut what is not, publish.