But this is Elon Musk we're talking about.
Instead of sending a private message, Musk tweeted directly at Carmack in front of his followers.
So, if you feel the need to ask Musk for a small loan of a million or maybe two million dollars, or just want someone to talk through your yearly holiday blues, go ahead and press those ten little digits.
He was apparently trying to send it to John Carmack, the chief technology officer of Facebook's Oculus virtual reality subsidiary. "My cell is..." the tweet read before it was deleted. Naturally it led to two things: people trying to call Musk and nearly as many wondering what he wanted to talk to the Facebook exec.
Facebook, who acquired Oculus in 2014, said Carmack isn't looking to leave the company, Bloomberg reported.
Elon Musk now operates his own electric self-driving auto company called Tesla and he might be wanting to incorporate the same technology into his vehicles.
As for the mobile number, CNBC called it to see if they could get Musk on the phone, only to be greeted by a message recorded by God of War creator David Jaffe. "Somehow you've found your way here to me".
While Business Insider isn't going to share the number, it does indeed appear to be Musk's personal phone - it registers as ready for Apple iMessage.