They may have been 'defined' wrong. and may not actually be in decimal degrees
They look like Web Mercator.
To find out what is going on...
Is your map coordinate system defined as being in decimal degrees? perhaps a GCS WGS84?
Did you calculate the values in the native units or in the coordinate system of the map?
Skip the field calculator and use one of the following
Add Geometry Attributes—Data Management toolbox | Documentation
and don't leave this optional, specify your data's coordinate system to make sure it is indeed in decimal degrees.
Coordinate_System (Optional) | The coordinate system in which the coordinates, length, and area will be calculated. The coordinate system of the input features is used by default. |
and be careful using this
Calculate Geometry Attributes—Data Management toolbox | Documentation
coordinate_system (Optional) | The coordinate system in which the coordinates, length, and area will be calculated. The coordinate system of the input features is used by default. For coordinate-based geometry properties, the coordinate system will only be applied when the coordinate format is the same as input; otherwise, the geographic coordinate system WGS_1984 will be used |
The field calculator can be dangerous unless you know what the output units will be.