Image via PaulAllen.com.

When you think of Microsoft and the men behind the company, one name probably comes to mind: Bill Gates. But most Microsoft fans also know that Gates did not found the company on his own, and Paul Allen, a childhood friend of Gates, is the company's cofounder.

Gates's name is more synonymous with Microsoft because he stuck with the company for a much longer period. But do you know when Allen left Microsoft? And why?

The answers to those questions are listed right here. Today is Paul Allen's birthday, and it's a big one; the man is now considered a "senior citizen" in the U.S. Today Allen is 65 years old. In honor of this momentous day in the life of a momentous man in Microsoft's storied history, we rounded up some quick facts about Allen.

Interesting tidbits about Microsoft Cofounder Paul Allen

  1. Paul Allen left Microsoft in 1983, just eight years after founding the company with Gates in 1975. But he didn't leave because of any specific business reasons, at least that we know of and at least not officially. Allen left the company due to his battle with Hodgkin's Lymphoma. Allen eventually beat that cancer.

  2. Allen met Gates when they were just young adolescents (14 and 12, respectively), while they were both students at Lakeside School in Seattle, Wash., according to Biography.com.

  3. Allen is a Washington State University (WSU) dropout. He only attended the school for two years, but he would later donate $26 million to build the Paul G. Allen School of Global Animal Health at WSU. (Gates is also a college dropout.)

  4. Paul Allen is No. 22 on Forbes's Wealthiest Americans of 2017 list, with a net worth of around $21 billion dollars. And that number is on the rise, according to Forbes. (Gates was No. 1 on that 2017 list with a net worth of about $92.1 billion. Yeah.)

  5. Allen is not only the twenty-second wealthiest American, according to Forbes, he is the thirteenth richest man in American tech and the forty-second richest American billionaire. (Gates has frequently held No. 1 in both of those categories, as well … Allen probably should have stuck with Microsoft, huh?)

  6. In his 2011 book, "Idea Man: A Memoir by the Cofounder of Microsoft," Allen accused both Gates and former CEO Steve Ballmer of "ripping him off." He was referring to an alleged conversation he overheard between Gates and Ballmer about schemes to reduce his share in the company.

  7. Allen owns or has partial ownership of three professional U.S. sports teams: the NFL's Seattle Seahawks (full owner), the NBA's Portland Trailblazers (full owner), and the MLS's Seattle Sounders (a partial stake in ownership).

  8. Allen not only beat Hodgkin's Lymphoma once, he beat cancer twice. More than two decades after his initial cancer diagnosis, Allen discovered that he had non-Hodgkin's Lymphoma. But he would go on to beat that disease, as well.

  9. Allen was a huge a Jimi Hendrix fan, according to Biography.com, and he played guitar in a band called Grown Men that released an album in 2000. And it's available on CD via Amazon …

  10. Allen is a bachelor … so, if you're single and you're located in the Mercer Island, Wash. area (where Allen lives), you might want to cozy on up to the guy. However, Allen does not seem like the marriage type. He's now 65, and he's never been married and has no kids. And he's actually known for his lavish parties ... for which he sometimes reportedly makes attendees sign non-disclosure agreements to attend.

Over to you ...

How many of these things did you already know about Paul Allen? If you didn't know all these facts, which one is most surprising to you?

Oh, and just in case the man stumbles upon this post, happy birthday Paul!

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