How to convert the date format - From DOUBLE to Datetime in KIbana elastic search

Elastic Stack Kibana
1

Could you please help with the below issue.

Is there anyway can we change the date format for the below mentioned columns?

Time_token : 1.6013861887237842E9

Created_at: 1.600254825E9

I want to create the dashboards by using the above date column but unable to develop it due to format issues

2

What is that field mapped as? Unless it's a timestamp, you will struggle.

3

It is mapped as string and showing symbol #