A secret hint

My first number is the same as the fifth

My last three numbers are an arithmetic progression with +1

My third digit is x, where 1/x is undefined

Subtract me from 0 and I am negative

Only one of my digits is a one

My second number is 9 (big hint)

My first is the square root of my favorite number

My favorite blog is the one with #youcanlearnanything spam

That’s like 5 hints

That’s my password for the next blog with a secret

PS it’s a six digit number LOL

PPS (or PSS?) you don’t need my favorite number