The business affairs of the corporation shall be managed and controlled by a board of directors, a president, a vice-president, a secretary, a treasurer, and such other officers and such agents as the corporation shall authorize by its bylaws. The board of directors shall consist of such number, not less than 15 nor more than 21, as shall be determined in the first instance by the incorporators and thereafter annually by the members and the shareholders of the corporation. The board of directors may exercise all the powers of the corporation except such as are conferred by law or by the bylaws of the corporation upon the shareholders or members and shall choose and appoint all the agents and officers of the corporation and fill all vacancies except vacancies in the office of director, which shall be filled as provided in this Code section. The annual meeting shall be held prior to May 1 or, if no annual meeting shall be held in the year of incorporation, then within 90 days after the approval of the articles at a special meeting as provided in this Code section. At such annual meeting or at each special meeting held as provided in this Code section, the members of the corporation shall elect two-thirds of the board of directors and the shareholders shall elect the remaining directors. The directors shall hold office until the next annual meeting of the corporation or special meeting held in lieu of the annual meeting after the election and until their successors are elected and qualified, unless sooner removed in accordance with provisions of the bylaws. Any vacancy in the office of a director elected by the members shall be filled by the directors elected by the members, and any vacancy in the office of a director elected by the shareholders shall be filled by the directors elected by the shareholders. Directors and officers shall not be responsible for losses unless the same shall have been occasioned by the willful misconduct of such directors and officers.