Vendor/phpspreadsheet/phpoffice/phpspreadsheet/src/PhpSpreadsheet/Calculation/Functions.php
public static function isEven($value = null)
    {
        $value = self::flattenSingleValue($value);

        if ($value === null) {
            return self::NAME();
        } elseif ((is_bool($value)) || ((is_string($value)) && (!is_numeric($value)))) {
            return self::VALUE();
        }

        return $value % 2 == 0;
    }
public static function isEven($value = null)
    {
        $value = self::flattenSingleValue($value);

        if ($value === null) {
            return self::NAME();
        } elseif ((is_bool($value)) || ((is_string($value)) && (!is_numeric($value)))) {
            return self::VALUE();
        }

        return $value % 2 == 0;
    }
IS_EVEN.

@param mixed $value Value to check

@return bool|string