Please read the following table in HTML format from a webpage and then answer the question in detail according to the table. Each table cell is defined by a <td> and a </td> tag. Each table row starts with a <tr> and ends with a </tr> tag. 'rowspan=m' and 'colspan=n' represents a cell spaning over 'm' rows and 'n' columns.

Webpage title:
Isotopes of plutonium
Table title:
Pu-240, Pu-241 and Pu-242
Table:
<table id='hittask' contenteditable='False'>
<tr> <th colspan=1 rowspan=2 > Isotope </th><th colspan=2 rowspan=1 > Thermal neutron cross section (barns) </th><th colspan=1 rowspan=2 > Decay Mode </th><th colspan=1 rowspan=2 > Half-life </th></tr>
<tr> <th colspan=1 rowspan=1 > Capture </th><th colspan=1 rowspan=1 > Fission </th></tr>
<tr> <td colspan=1 rowspan=1 > 238U </td><td colspan=1 rowspan=1 > 2.683 </td><td colspan=1 rowspan=1 > 0.000 </td><td colspan=1 rowspan=1 > α </td><td colspan=1 rowspan=1 > 4.468 x 109 years </td></tr>
<tr> <td colspan=1 rowspan=1 > 239U </td><td colspan=1 rowspan=1 > 20.57 </td><td colspan=1 rowspan=1 > 14.11 </td><td colspan=1 rowspan=1 > β </td><td colspan=1 rowspan=1 > 23.45 minutes </td></tr>
<tr> <td colspan=1 rowspan=1 > 239Np </td><td colspan=1 rowspan=1 > 77.03 </td><td colspan=1 rowspan=1 > – </td><td colspan=1 rowspan=1 > β </td><td colspan=1 rowspan=1 > 2.356 days </td></tr>
<tr> <td class="highlighted"  colspan=1 rowspan=1 > 239Pu </td><td colspan=1 rowspan=1 > 270.7 </td><td colspan=1 rowspan=1 > 747.9 </td><td colspan=1 rowspan=1 > α </td><td class="highlighted"  colspan=1 rowspan=1 > 24,110 years </td></tr>
<tr> <td colspan=1 rowspan=1 > 240Pu </td><td colspan=1 rowspan=1 > 287.5 </td><td colspan=1 rowspan=1 > 0.064 </td><td colspan=1 rowspan=1 > α </td><td colspan=1 rowspan=1 > 6,561 years </td></tr>
<tr> <td colspan=1 rowspan=1 > 241Pu </td><td colspan=1 rowspan=1 > 363.0 </td><td colspan=1 rowspan=1 > 1012 </td><td colspan=1 rowspan=1 > β </td><td colspan=1 rowspan=1 > 14.325 years </td></tr>
<tr> <td class="highlighted"  colspan=1 rowspan=1 > 242Pu </td><td colspan=1 rowspan=1 > 19.16 </td><td colspan=1 rowspan=1 > 0.001 </td><td colspan=1 rowspan=1 > α </td><td class="highlighted"  colspan=1 rowspan=1 > 373,300 years </td></tr>
</table>
Question:
Which two isotopes of plutonium have the longest half-lives?
Answer:
Pu-242, with a half-life of 373,300 years, and Pu-239, with a half-life of 24,110 years.