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:
| Episode | Title | Date of emission | Audience | Share |
| --- | --- | --- | --- | --- |
| FIRST SEASON | FIRST SEASON | FIRST SEASON | FIRST SEASON | FIRST SEASON |
| 1 | Los monstruos no hacen cosquillas | 24 May 2007 | 4.629.000 | 25,8% |
| 2 | Todo el mundo tiene un secreto | 31 May 2007 | 4.590.000 | 25,4% |
| 3 | Ojos que no ven | 7 June 2007 | 3.601.000 | 20,8% |
| 4 | Un mensaje en una botella | 14 June 2007 | 4.200.000 | 23,5% |
| 5 | Un cadáver en la laguna | 21 June 2007 | 3.726.000 | 23,0% |
| 6 | La noche de Santa Isabel | 28 June 2007 | 3.717.000 | 24,7% |
| SECOND SEASON | SECOND SEASON | SECOND SEASON | SECOND SEASON | SECOND SEASON |
| 7 | ¿Con qué sueñan los peces? | 7 November 2007 | 3.073.000 | 16,9% |
| 8 | Persiguiendo luciérnagas | 14 November 2007 | 3.268.000 | 19,1% |
| 9 | El anillo | 21 November 2007 | 3.636.000 | 19,9% |
| 10 | La caja de música | 28 November 2007 | 3.491.000 | 19,8% |
| 11 | En orden alfabético | 5 December 2007 | 3.294.000 | 19,3% |
| 12 | Ver para creer | 12 December 2007 | 3.552.000 | 19,8% |
| 13 | Mi amigo el monstruo | 19 December 2007 | 3.896.000 | 21,4% |
| 14 | El polo norte | 2 January 2008 | 4.693.000 | 25,4% |
| THIRD SEASON | THIRD SEASON | THIRD SEASON | THIRD SEASON | THIRD SEASON |
| 15 | El búho | 23 April 2008 | 3.695.000 | 21,8% |
| 16 | 8 milímetros | 30 April 2008 | 3.341.000 | 20,8% |
| 17 | El soldadito de plomo | 7 May 2008 | 3.310.000 | 17,4% |
| 18 | En el fondo del mar | 14 May 2008 | 3.155.000 | 20,5% |
| 19 | La vida es sueño | 28 May 2008 | 3.461.000 | 20,8% |
| 20 | La peor cárcel del mundo | 4 June 2008 | 3.196.000 | 18,4% |
| 21 | El fantasma de la profesora decapitada | 11 June 2008 | 3.428.000 | 20,4% |
| 22 | Los cinco vengadores | 18 June 2008 | 3.267.000 | 19,8% |
| 23 | La noche del fuego | 25 June 2008 | 3.944.000 | 24,0% |
Question:
What was the audience for Episode 21?
Answer:
3428000.0