Sunday Times Teaser 2510 – No Title

by Danny Roth

Published October 31 2010 (link)

Since we last met them, George has moved departments yet again and Martha has forgotten the extension number.

“No problem,” said the operator.

“If you write down the number itself, the average of its four digits, the sum of its four digits, and the cube root of the difference between the number and its reverse (which is smaller), then you will write no digit more than once.”

What is George’s new extension number?