Somehow I think the opposite -- that mathematics is discovered, not invented. I think it has something to do, not with utility, but with the search for Truth.
I can't think of how to distinguish discovery from invention in mathematics, but there is the problem that mathematical systems cannot prove their own truth. That seems a strike against the assertion that mathematics is God's alphabet.
Does threeness exist separately from 3 chairs, 3 apples, 3 dogs?
Did Einstein discover general and special relativity or did he invent them?