The number of Content Version limit depends on the Salesforce Edition. You can check the details of Salesforce CRM Content Limits here.
The number of Attachments that can be added to Content per 24 hours is 2500 by default. So, if you want to import 26000 files the migration will last 11 days.
To solve the issue, you can request Salesforce.com Support the limit increase in line with the requirements of the project. More information about increasing the maximum number of ‘Content Versions’ you can find here.