Custom formatting string in .NET makes it really easy.
static void Job61(Args _args)
{
System.DateTime dateTime = System.DateTime::get_UtcNow();
str utcTimeAsStr = dateTime.ToString('yyyyMdd_HHmmss');
info(strFmt("Datetime in GMT: %1",utcTimeAsStr));
}
This code achieves this output
Datetime in GMT: 20211105_113052