A restatement of what Cynthia wrote, but expressed differently.
SAS stores numbers or characters.
Dates are simply/essentially formatted numbers.
Times are simply/essentially formatted numbers.
A Date format assumes 1 = 1 day, and 0 = January 1, 1960
A Time format assumes 1 = 1 second, and 0 = 00:00:00
A DateTime format assumes 1 = 1 second and 0 = 00:00:00 on January 1, 1960
Your data was apparently created to represent a date, not a datetime value.
The format you are using is a datetime format, that is what the "DT" prefix to the format name means.
Today = 17,657 days after January 1, 1960
Right now = 39,977 seconds after midnight (00:00:00)
Right now = 1525604777 seconds after 00:00:00 on January 1, 1960
So, today expressed as a datetime value would be 01JAN1960:04:54:17