maatwebsite lost precision when export long integer data

Maatwebsite would lost precision when export long integer data, no matter string or int storaged in database.   Implementing MaatwebsiteExcelConcernsWithCustomValueBinder can solve this issue in your export class. You should change dataTypeForValue method like following.

/** Bind value to a cell.
     *
     * @param Cell $cell Cell to bind value to
     * @param mixed $value Value to bind in cell
     *
     * @return bool
     */
    public function bindValue(Cell $cell, $value)
    {
        // sanitize UTF-8 strings
        if (is_string($value)) {
            $value = StringHelper::sanitizeUTF8($value);
        } elseif (is_object($value)) {
            // Handle any objects that might be injected
            if ($value instanceof DateTimeInterface) {
                $value = $value->format('Y-m-d H:i:s');
            } elseif (!($value instanceof RichText)) {
                $value = (string) $value;
            }
        }

        // Set value explicit
        $cell->setValueExplicit($value, static::dataTypeForValue($value));

        // Done!
        return true;
    }

    /**
     * DataType for value.
     *
     * @param mixed $pValue
     *
     * @return string
     * @SuppressWarnings(PHPMD.CyclomaticComplexity)
     */
    public static function dataTypeForValue($pValue)
    {
        // Match the value against a few data types
        if ($pValue === null) {
            return DataType::TYPE_NULL;
        } elseif ($pValue === '') {
            return DataType::TYPE_STRING;
        } elseif ($pValue instanceof RichText) {
            return DataType::TYPE_INLINE;
        } elseif ($pValue[0] === '=' && strlen($pValue) > 1) {
            return DataType::TYPE_FORMULA;
        } elseif (is_bool($pValue)) {
            return DataType::TYPE_BOOL;
        } elseif (is_float($pValue) || is_int($pValue)) {
            return DataType::TYPE_NUMERIC;
        } elseif (preg_match('/^[+-]?(d+\.?d*|d*\.?d+)([Ee][-+]?[0-2]?d{1,3})?$/', $pValue)) {
            $tValue = ltrim($pValue, '+-');
            if (is_string($pValue) && $tValue[0] === '0' && strlen($tValue) > 1 && $tValue[1] !== '.') {
                return DataType::TYPE_STRING;
            } elseif ((strpos($pValue, '.') === false) && ($pValue > PHP_INT_MAX)) {
                return DataType::TYPE_STRING;
            }

            return DataType::TYPE_STRING;
        } elseif (is_string($pValue)) {
            $errorCodes = DataType::getErrorCodes();
            if (isset($errorCodes[$pValue])) {
                return DataType::TYPE_ERROR;
            }
        }

        return DataType::TYPE_STRING;
    }

The only one different is in line 60, author return  DataType::TYPE_NUMERIC