According to an Instagram cofounder, there are 2 things you should look for in a business partner

As Instagram cofounder and CTO Mike Krieger said, Silicon Valley is littered with the corpses of business partnerships.

In a discussion with the New Yorker's online editor Nick Thompson this March at the 92Y in New York City, Krieger said that he "can't stress how rare it is" that he and his cofounder, CEO Kevin Systrom, are still friends after working together since 2009.

It's even more surprising, Thompson added, given that Instagram went from a tiny startup to a billion-dollar company when it was acquired by Facebook for $1 billion in 2012.

There are two essential factors for a successful business partnership, Krieger explained.

1. You need to tolerate working next to that person for days on end (even when they don't shower).

The week Krieger and Systrom launched Instagram in October 2010, neither left their San Francisco office.

"Kevin ran out of underwear, and if you can work with somebody for a week who's in the same pair of underwear, you're probably set for life," Krieger said, laughing.

A business partnership is in many ways like a marriage, and part of both is learning to accept your partner in an intimate way, warts and all. In Krieger's case, this meant the acceptance of working together with Systrom in close quarters, and no showers.

2. Your skill sets need to complement each other.

When they decided to work together, they made it clear from the outset that Systrom would take care of business operations and Krieger the engineering side, and meet in the middle for overall product development.

"He's really excited about the running Instagram part, making sure that we're a sustainable business, like how do we integrate within Facebook," Krieger said. "I'm really excited about the technology side and we come together on product. So having that Venn diagram has worked nicely."

Founders who think they can equally split the same duties and have the same level of influence are deceiving themselves, Krieger explained. "Because what I think usually goes wrong is where you have co-CEOs or two people who want the same job, and I think that gets really, really messy," he said.

"So I'm really happy that six years in we're still good friends and it works well."

We first heard the interview in the latest episode of the New Yorker Radio Hour podcast, which you can listen to below.