Where can I find the phone number of the SIM card that I have in an iPad?

Is there a way, directly on the iPad, to find out which phone number is associated to the MicroSIM which it is using?

I can't find it in the menus, currently.

Is there an easy way to find it directly, like on an iPhone?

Settings → General → About → Celluar Data Number

From the device, you can get this through Settings > Tap General > Tap About > Scroll to view the IMEI/ICCID/my Number.

Settings → General → About → Celluar Data Number should theoretically work, but on many iPads it doesn't. See also

Cellular Data Number is "Unknown" on some iPads

Our provider is AT&T, and on my account pages, e.g., https://www.att.com/my/#/wirelessUsage, I can see the "phone" number for the iPad.