Tuesday 3 April 2018

Can you solve this?
I am a number between 7 000 000 and 8 000 000. All my digits are odd. All the digits in my thousands period are the same. All the digits in my units (ones) period are the same. The sum of all my digits is 31. What number am I? Give as many answers as you can. What strategies did you use to find the mystery number?