Please read the following table in Markdown format and then answer the question according to the table. Table cells in one row are seperated by '|', and different rows are seperated by '
'.

Table:
| № | # | Title | Directed by | Written by | Original air date | Production code | U.S. viewers (million) |
| --- | --- | --- | --- | --- | --- | --- | --- |
| 44.0 | 1.0 | " Olivia " | Joe Chappelle | J. H. Wyman & Jeff Pinkner | September23,2010 | 3X6101 | 5.83 |
| 45.0 | 2.0 | " The Box " | Jeffrey Hunt | Josh Singer & Graham Roland | September30,2010 | 3X6102 | 5.24 |
| 46.0 | 3.0 | " The Plateau " | Brad Anderson | Alison Schapker & Monica Owusu-Breen | October7,2010 | 3X6103 | 5.19 |
| 47.0 | 4.0 | " Do Shapeshifters Dream of Electric Sheep? " | Ken Fink | David Wilcox & Matthew Pitts | October14,2010 | 3X6104 | 5.22 |
| 48.0 | 5.0 | " Amber 31422 " | David Straiton | Josh Singer & Ethan Gross | November4,2010 | 3X6105 | 4.80 |
| 49.0 | 6.0 | " 6955 kHz " | Joe Chappelle | Robert Chiappetta & Glen Whitman | November11,2010 | 3X6106 | 4.82 |
| 50.0 | 7.0 | " The Abducted " | Chuck Russell | David Wilcox & Graham Roland | November18,2010 | 3X6107 | 4.85 |
| 51.0 | 8.0 | " Entrada " | Brad Anderson | Jeff Pinkner & J. H. Wyman | December2,2010 | 3X6108 | 5.13 |
| 52.0 | 9.0 | " Marionette " | Joe Chappelle | Monica Owusu-Breen & Alison Schapker | December9,2010 | 3X6109 | 4.74 |
| 53.0 | 10.0 | " The Firefly " | Charles Beeson | J. H. Wyman & Jeff Pinkner | January21,2011 | 3X6110 | 4.87 |
| 54.0 | 11.0 | " Reciprocity " | Jeannot Szwarc | Josh Singer | January28,2011 | 3X6111 | 4.53 |
| 55.0 | 12.0 | " Concentrate and Ask Again " | Dennis Smith | Graham Roland & Matthew Pitts | February4,2011 | 3X6112 | 4.26 |
| 56.0 | 13.0 | " Immortality " | Brad Anderson | David Wilcox & Ethan Gross | February11,2011 | 3X6113 | 3.74 |
| 57.0 | 14.0 | " 6B " | Thomas Yatsko | Glen Whitman & Robert Chiappetta | February18,2011 | 3X6114 | 4.02 |
| 58.0 | 15.0 | " Subject 13 " | Frederick E. O. Toye | Jeff Pinkner & J. H. Wyman & Akiva Goldsman | February25,2011 | 3X6115 | 4.02 |
| 59.0 | 16.0 | " Os " | Brad Anderson | Josh Singer & Graham Roland | March11,2011 | 3X6116 | 3.64 |
| 61.0 | 18.0 | " Bloodline " | Dennis Smith | Alison Schapker & Monica Owusu-Breen | March25,2011 | 3X6118 | 3.84 |
| 63.0 | 20.0 | " 6:02 AM EST " | Jeannot Szwarc | David Wilcox & Josh Singer & Graham Roland | April22,2011 | 3X6120 | 3.33 |
Question:
What episode number had US viewership of 4.87 million?
Answer:
53.0