Yes, Ukraine is the largest European country (but it is not in the European Union).
There is none. The area code 375 will not allow you to call anywhere, however, if one used the number as a prefix for a number, it would allow someone to call Belarus from any other country. Belarus is a country very close to Ukraine in Europe.
The country code and area code of Beshenkovichi, Belarus is 375, (8~0)2131.
The country code and area code of Mogilev, Belarus is 375, (8~0)222.
The country code and area code of Novopolotsk, Belarus is 375, (8~0)214.
The country code and area code of Shchuchin, Belarus is 375, (8~0)1514.
The country code and area code of Oshmyanu, Belarus is 375, (8~0)1593.
The country code and area code of Postavu, Belarus is 375, (8~0)2155.
The country code and area code of Korelichi, Belarus is 375, (8~0)1596.
The country code and area code of Lida, Belarus is 375, (8~0)1561.
The country code and area code of Belunichi, Belarus is 375, (8~0)2232.
The country code and area code of Berestovitsa, Belarus is 375, (8~0)1511.