Daylight robbery

A Maths teacher was an eye-witness to a robbery. Everything happened very quickly, but she was able to remember the number on the robber's T-shirt. When she got home, she wrote the number down. She also wrote down some clues about the number. She then gave the clues to her pupils to see if they could work out the number.

Can you work out the number from the clues?

• It is an odd number
• It has 4 digits
• It is divisible by both 3 and 9
• When it is divided by 21, there is no remainder
• All the digits are different
• The total of the first two digits is double the totals of the last two digits
• The number is between 2999 and 5000