how can I generate a random 6 digits number with this rule? BY PHP

I have a function called rndgen() generate random 6 digits number that can have zero digit everywhere even beginning of number.

example:

267809

671485

200000

037481

000005

000437

How can I check this number if more than three digits are the beginning or end of the zero, it would create a new number, but if the zeros were at the beginning or end, lower or none could use the same number( BY PHP )?

thanks