00 isn't part of the country code, it is a commonly used international access prefix.
Telephone country code +49 is Germany. +49 61 is an incomplete area code in the Rhine-Main area. You need 1 or 2 more digits to be more specific.
(The plus sign means "insert your international access prefix here." From a GSM mobile phone, you can enter the number in full international format, starting with the plus sign. The most common prefix is 00, but North America (USA, Canada, etc.) uses 011, Japan uses 010, Australia uses 0011, and many other countries use different prefixes.)
There is not a country that has a phone number starting with 54321. The number does come up on some calls, but has been reported as a scam.
That is not a valid mobile number. There is no country code starting with a sequence of zeros.
That's a UK number - HOWEVER - numbers starting with 06 in the UK are not in use yet.
The largest country in terms of population starting with the letter "A" is Afghanistan.
Afghanistan
Belgium
Djiboti
Best guess is that you are asking about a telephone number starting with +1 610 36, which is in telephone country code +1 (North America, including USA, Canada, etc.), area code 610 (suburbs of Philadelphia, Pennsylvania).
a seed starting to grow
These vary from country to country.
1999uqxj is not a number and is therefore not a country code number.
The country code for Honduras is 504. So to send a fax to Honduras, use 011 + 504 + the local number in Honduras (an 8-digit number, generally starting with a "2").