Who is the largest unicorn in the world?

I'm curious, who holds the title of being the largest unicorn in the world? Are we referring to a startup company that has achieved immense valuation but has yet to go public, or is there another context to this question? If it's the former, I'm intrigued to know which company has managed to amass such a staggering valuation without the need for an IPO. And what are some of the key factors that have contributed to their success and growth?