Acorns the micro-investment app that sets up a portfolio for you by collecting your spare change, has today announced the close of a $23 million Series C financing, led by Greycroft Ventures and e.Ventures, with participation from Sound Ventures, Garland Capital, and MATH Venture Partners.

This brings Acorns’ total amount raised to $32 million.

The company, which rounds up to the next dollar on every user transaction and invests it into a customizable portfolio, says that it has grown to 650,000 members with around half of them opening up investment accounts on the platform. Acorns also says that it’s processed over 28 million trades and linked more than a million debit and credit cards to the platform.

Acorns claims to be the world’s first mobile investment platform, letting users attach their credit cards, debit cards, etc. and make deposits or withdrawals at will. But the special sauce of Acorns lies in its sticky-handed grab at your spare change. On every transaction made on attached credit or debit cards, Acorns automatically rounds up to the nearest dollar and takes the spare change, placing it into your investment portfolio. Obviously, users can opt out of that, or set up a system to go in daily and choose which transactions should be rounded up.

Users also have control over the type of portfolio they choose, with five options ranging from conservative to aggressive.

“We’re creating new investors, and as they grow one of our greatest challenges will be really improving education,” said cofounder Jeff Cruttenden. “People have questions about how Acorns is supposed to work for them and we want to invest in making sure that the investors we create are being educated the whole way through.”