The following information pertains to J Company's outstanding stock for 2021:

Common stock, $1 par
Shares outstanding, 1/1/2021	15,500
2 for 1 stock split, 4/1/2021	15,500
Shares issued, 7/1/2021	6,100
Preferred stock, $100 par, 5% cumulative
Shares outstanding, 1/1/2021	5,100

What is the number of shares J should use to calculate 2021 basic earnings per share?