If you are not a professional mathematician I'm not sure why you're interested in the legitimacy of a math journal. (That may sound elitist. It is not intended to be: really, I don't understand why someone else would need to worry about this.) If you are then you should be able to look at a journal's webpage and evaluate it yourself. Wondering whether a journal might be legitimate because it has a certain impact factor is a bit like measuring the Chinese emperor's nose by asking everyone in China when you are the emperor's barber. There is no reason to look at statistical measurements done by others of absolutely uncertain fidelity when you can just see for yourself. (But to be honest: I did notice the text about the impact factor described in o4tlulz's answer.)
I had never heard of this journal before, but 15 minutes on its webpage allowed me to come to a conclusion regarding its legitimacy. I looked at the editorial board, the publication policy and then started skimming papers: some just to get a general sense and then a smaller number in areas of mathematics that I know relatively well. I stopped looking when I saw this paper, which was as decisive a confirmation of the impression I had acquired as one could possibly hope for.