Excel file generated in php and mysql does not open?

I have the following code that creates the file in excel but it does not open and he opened it with my code editor.

<?php

    require 'Classes/PHPExcel/IOFactory.php';
    require 'conexion.php';

    $sql = "SELECT id, nombre, precio, existencia FROM productos";
    $resultado = $mysqli->query($sql);

    $fila = 2;

    $objPHPExcel = new PHPExcel();
    $objPHPExcel->getProperties()->setCreator("C.T")->setDescription("Reporte de Productos");

    $objPHPExcel->setActiveSheetIndex(0);
    $objPHPExcel->getActiveSheet()->setTitle("Productos");

    $objPHPExcel->getActiveSheet()->setCellValue('A1', 'ID');
    $objPHPExcel->getActiveSheet()->setCellValue('B1', 'NOMBRE');
    $objPHPExcel->getActiveSheet()->setCellValue('C1', 'PRECIO');
    $objPHPExcel->getActiveSheet()->setCellValue('D1', 'EXISTENCIA');
    $objPHPExcel->getActiveSheet()->setCellValue('E1', 'TOTAL');

    while($row = $resultado->fetch_assoc())
    {

        $objPHPExcel->getActiveSheet()->setCellValue('A'.$fila, $row['id']);
        $objPHPExcel->getActiveSheet()->setCellValue('B'.$fila, $row['nombre']);
        $objPHPExcel->getActiveSheet()->setCellValue('C'.$fila, $row['precio']);
        $objPHPExcel->getActiveSheet()->setCellValue('D'.$fila, $row['existencia']);
        $objPHPExcel->getActiveSheet()->setCellValue('E'.$fila, '=C'.$fila.'*D'.$fila);

        $fila++;

    }

    header("Content-Type: application/vnd.openxmlformats-officedocument.spreadsheetml.sheet");
    header('Content-Disposition: attachment;filename="Productos.xlsx"');
    header('Cache-Control: max-age=0');

    $objWriter = new PHPExcel_Writer_Excel2007($objPHPExcel);
    $objWriter->save('php://output');

?>

And show me this:

  

0950 4b03 0414 0002 0008 0082 4aa4 4c47   9244 b258 0100 00f0 0400 0013 0000 005b   436f 6e74 656e 745f 5479 7065 735d 2e78   6d6c ad94 4d4e c330 1085 f79c 22f2 1625   6e59 2084 9a76 4161 0995 2807 30f6 a4b1   ead8 9667 fa77 7b26 690b 0889 40d5 6e62   45f6 7bdf f879 ecd1 64db b86c 0d09 6df0   a518 1603 9181 d7c1 58bf 28c5 dbfc 29bf   1319 92f2 46b9 e0a1 143b 4031 195f 8de6   bb08 98b1 d863 296a a278 2f25 ea1a 1a85   4588 e079 a60a a951 c4bf 6921 a3d2 4bb5   0079 3318 dc4a 1d3c 81a7 9c5a 0f31 1ebd   303f 5903 d94c 257a 560d 63e4 d649 6237   d87f 8705 fb89 ec61 2f6c d9a5 5031 3aab   1571 e172 edcd 0f6a 1eaa ca6a 3041 af1a   9614 9dcd 75eb 227f 0522 ed1c e0d9 288c   0994 c11a 801a 57ec 4d8f e429 546a e528   7bdc b2fb 3ef3 040e 4fe3 1dc2 2c58 d9ad   c1da c63e 42ff 867e d7ad cf0c 82f5 d3a4   36dc 4a3d a16f 425a be87 b0bc 74ec ed58