Financial report context:
our previously announced stock repurchase program , and any subsequent stock purchase program put in place from time to time , could affect the price of our common stock , increase the volatility of our common stock and could diminish our cash reserves . such repurchase program may be suspended or terminated at any time , which may result in a decrease in the trading price of our common stock . we may have in place from time to time , a stock repurchase program . any such stock repurchase program adopted will not obligate the company to repurchase any dollar amount or number of shares of common stock and may be suspended or discontinued at any time , which could cause the market price of our common stock to decline . the timing and actual number of shares repurchased under any such stock repurchase program depends on a variety of factors including the timing of open trading windows , the price of our common stock , corporate and regulatory requirements and other market conditions . we may effect repurchases under any stock repurchase program from time to time in the open market , in privately negotiated transactions or otherwise , including accelerated stock repurchase arrangements . repurchases pursuant to any such stock repurchase program could affect our stock price and increase its volatility . the existence of a stock repurchase program could also cause our stock price to be higher than it would be in the absence of such a program and could potentially reduce the market liquidity for our stock . there can be no assurance that any stock repurchases will enhance stockholder value because the market price of our common stock may decline below the levels at which we repurchased shares of common stock . although our stock repurchase program is intended to enhance stockholder value , short-term stock price fluctuations could reduce the program 2019s effectiveness . additionally , our share repurchase program could diminish our cash reserves , which may impact our ability to finance future growth and to pursue possible future strategic opportunities and acquisitions . see item 5 . market for registrant 2019s common equity , related stockholder matters and issuer purchases of equity securities and note 10 - repurchases of common stock included in part ii of this form 10-k for further information . item 1b . unresolved staff comments item 2 . properties as of december 31 , 2017 , our significant properties that we primarily leased and were used in connection with switching centers , data centers , call centers and warehouses were as follows: .

Financial table:
approximate number: switching centers; approximate size in square feet: 61; column_3: 1300000
approximate number: data centers; approximate size in square feet: 6; column_3: 500000
approximate number: call center; approximate size in square feet: 17; column_3: 1400000
approximate number: warehouses; approximate size in square feet: 15; column_3: 500000

Additional report context:
as of december 31 , 2017 , we primarily leased : 2022 approximately 61000 macro sites and approximately 18000 distributed antenna system and small cell sites . 2022 approximately 2200 t-mobile and metropcs retail locations , including stores and kiosks ranging in size from approximately 100 square feet to 17000 square feet . 2022 office space totaling approximately 900000 square feet for our corporate headquarters in bellevue , washington . we use these offices for engineering and administrative purposes . 2022 office space throughout the u.s. , totaling approximately 1700000 square feet as of december 31 , 2017 , for use by our regional offices primarily for administrative , engineering and sales purposes . in february 2018 , we extended the leases related to our corporate headquarters facility . item 3 . legal proceedings see note 13 - commitments and contingencies of the notes to the consolidated financial statements included in part ii , item 8 of this form 10-k for information regarding certain legal proceedings in which we are involved. .

Question: what is the average size ( in square feet ) of switching centers in 2017?
Answer: 21311.48