A cooperative credit union may receive the savings of its members in payment for shares, may lend to its members at reasonable rates of interest, not to exceed the rate authorized by law, or may invest, as provided by law, the funds so accumulated, may borrow from banks, savings and loan associations, trust companies, or other credit unions, or persons, and loan such money to its members, and may undertake such other activities authorized by law, provided that any credit union may loan money to any other credit union at such rate as the parties to the loan may agree.