There is no area code +1 821 in North America (USA, Canada, etc.).
Country code +82 is South Korea, and +82 1 is the beginning of a mobile number.
Mexican area code 821 (+52 821 for landlines, +52 1 821 for mobiles) is Linares, Nuevo Leon.
(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 no area code +1 851 in North America.
The country code and area code of Brahmanbaria, Bangladesh is 880, (0)851.
The country code and area code of Passau, Germany is 49, (0)851.
The country code and area code of Shahat, Libya is 218, (0)851.
The country code and area code of Guiyang- GZ, China is 86, (0)851.
The country code and area code of Alava, Spain is 34, 845.
64% of 851= 64% * 851= 0.64 * 851= 544.64
The country code and area code of Astrakhan, Russian Federation is 7, (8)8512.
The factors of 851 are: 1 23 37 851
1 x 851, 23 x 37 = 851
851 = DCCCLI
293 + 851 = 1144