Identifying SobjectType Dyanamically

getKeyPrefix of Schema.getGlobalDescribe can be used to identify dynamically the SobjectType in Apex.

String prefix = recordId.substring(0,3);
String objectType;
Map<String, Schema.SObjectType> gd = Schema.getGlobalDescribe();
for(Schema.SObjectType s : gd.values()){
    if(prefix == s.getDescribe().getKeyPrefix()){
        objectType = s.getDescribe().Name;
    }
}

recordId consists the Id of the sobject Record for whose SobjectType needs to be identified. Above piece of code does it well.