You can simply download iRoot APK latest version and install it on your device. Since this app is quite popular, there are a lot of available versions out there.

App NameiRoot
Size13.7 MB

Hence, you can have a hard time finding the correct version of iRoot. Not only that but making sure that you are using an official download link to get this app is also important. Because if you are not, you might end up installing a malicious version of iRoot on your device.