1-how many addresses are there with this characteristic?
If you're talking about funded addresses: you can get the data from List of all Bitcoin addresses with a balanceIf you want to know this for all Bitcoin addresses ever used, I can get you the data, but I still don't have a VPS for it.
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3- as these types of addresses are considerably strange and proportionally in less quantity
You may be interested in Rare address hall of fame 
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Does the owner of "1LdRcdxfbSnmCYYNdeYpUnztiYzVfBEQeC" have a strangely vulnerable address?
With 3 billion dollars in it, It would have been long gone if it wouldn't be secure. My first assumption was it's an old address and the owner must have lost access, but it was funded in 2014 with (at the time) 31 million dollars. So my new assumption is the owner knew exactly what he was doing, and is just hodling his coins.Quote
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It's better to remove this request, and put the Bitcoin address in your profile.I'd be interested if you could change it to numbers and release the times it takes to generate those addresses though (I think it should take about 49/9=5.44x longer - but I'm not that sure).
My guess it it takes much, much longer than that. I don't think it's possible to generate a Bitcoin address with only numbers.