A crop factor of 1.6 is used when the sensor is 1.6× smaller (linearly) than a 35mm film frame (usually measured across the diagonal).

In this case, the sensor is much smaller than that — in fact, apparently 5.5× smaller than a 35mm film frame. The SX520HS is a super-zoom compact (sometimes called a "bridge camera", although I think that's a fairly misleading marketing term), and cameras in this category usually have small sensors, which is one of the ways they can have such amazing zoom versatility and "reach" in a package that weighs less than a pound.

You can see in the camera specifications under "Image Capture Device" that this camera uses a 1/2.3-inch CMOS sensor. Read about this "inch" designation here if you're curious, but in practice, this usually means a chip measuring about 6.2mm × 4.6mm. That's about 7.7mm diagonally, and compared to the ~43.3mm diagonal of the 35mm film reference standard, gives a crop factor of ~5.6×. It appears (from the 5.5× value) that this camera's sensor is slightly bigger than that, but not enough to label it something outside of the 1/2.3"-class.]

So, the specs aren't misleading at all. In fact, they show exactly why we still use this reference even though few people use 35mm film (and "full-frame" digital sensors are still high-end gear rather than common in general consumer devices). Using the equivalence makes it easy for consumers to understand the zoom and field of view they'll get from a camera like this when compared to competing models which may have slightly bigger or smaller sensors.