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:
| Administrative division | Area (km²) 2011** | Population 2001 Census (Adjusted) | Population 2011 Census (Adjusted) | Population density (/km² 2011) |
| --- | --- | --- | --- | --- |
| Dhaka District | 1,463.6 | 9036647.0 | 12517361.0 | 8,552.4 |
| => Savar Upazila | 282.11 | 629695.0 | 1442885.0 | 5,114.6 |
| => Keraniganj Upazila | 166.82 | 649373.0 | 824538.0 | 4,942.68 |
| Narayanganj District | 684.37 | 2300514.0 | 3074078.0 | 4,491.8 |
| => Narayanganj Sadar Upazila | 100.74 | 946205.0 | 1381796.0 | 13,716.5 |
| => Bandar Upazila | 54.39 | 267021.0 | 327149.0 | 6,014.8 |
| => Rupganj Upazila | 176.48 | 423135.0 | 558192.0 | 3,162.9 |
| Gazipur District | 1,806.36 | 2143200.0 | 3548115.0 | 1,964.2 |
| => Gazipur Sadar Upazila | 457.67 | 925454.0 | 1899575.0 | 4,150.5 |
| => Kaliakair Upazila | 314.13 | 278967.0 | 503976.0 | 1,604.3 |
| Narsingdi District | 1,150.14 | 1983499.0 | 2314899.0 | 2,012.7 |
| => Narsingdi Sadar Upazila | 213.43 | 606474.0 | 737362.0 | 3,454.8 |
| => Palash Upazila | 94.43 | 198106.0 | 221979.0 | 2,350.7 |
Question:
What was the population density in km2 for 2011 in the division where area in km2 was 684.37 in 2011? 
Answer:
4491.8