21.2:

```
milovidov-desktop :) SELECT CAST(1111111111.222 AS DateTime64(3))

SELECT cast(1111111111.222, 'DateTime64(3)')

Query id: d10c8623-5c74-4a38-b535-a99f6af4d28d

┌─cast(1111111111.222, 'DateTime64(3)')─┐
│               2005-03-18 04:58:31.222 │
└───────────────────────────────────────┘
```

master:

```
milovidov-desktop :) SELECT CAST(1111111111.222 AS DateTime64(3))

SELECT cast(1111111111.222, 'DateTime64(3)')

Query id: cb4af967-a4ae-4df5-89ba-234d68675f93

┌─cast(1111111111.222, 'DateTime64(3)')─┐
│               2005-03-18 04:58:31.000 │
└───────────────────────────────────────┘
```
{
        TypeIndex from_type_index = from_type->getTypeId();
        WhichDataType which(from_type_index);
        bool can_apply_accurate_cast = (cast_type == CastType::accurate || cast_type == CastType::accurateOrNull)
            && (which.isInt() || which.isUInt() || which.isFloat());
        if (requested_result_is_nullable && checkAndGetDataType<DataTypeString>(from_type.get()))
        {
            
            
            FunctionPtr function = FunctionConvertFromString<ToDataType, NameCast, ConvertFromStringExceptionMode::Null>::create();
            return createFunctionAdaptor(function, from_type);
        }
        else if (!can_apply_accurate_cast)
        {
            FunctionPtr function = FunctionTo<ToDataType>::Type::create();
            return createFunctionAdaptor(function, from_type);
        }
        auto wrapper_cast_type = cast_type;
        return [wrapper_cast_type, from_type_index, to_type]
            (ColumnsWithTypeAndName & arguments, const DataTypePtr & result_type, const ColumnNullable *column_nullable, size_t input_rows_count)
        {
            ColumnPtr result_column;
            auto res = callOnIndexAndDataType<ToDataType>(from_type_index, [&](const auto & types) -> bool {
                using Types = std::decay_t<decltype(types)>;
                using LeftDataType = typename Types::LeftType;
                using RightDataType = typename Types::RightType;
                if constexpr (IsDataTypeNumber<LeftDataType> && IsDataTypeNumber<RightDataType>)
                {
                    if (wrapper_cast_type == CastType::accurate)
                    {