Undefined index json_decode php_curl

hello friends I try to get a field of this json that I get from a query with php curl:

<?php

$ruta = "https://ruc.com.pe/api/beta/ruc";
$token = "808e687d-3960-43c1-9a75-c102cdecf1a4-77600153-fcd3-4a2e-a1f8-1327b";

$rucaconsultar = '10486113532';

$data = array(
    "token" => $token,
    "ruc"   => $rucaconsultar
);

$data_json = json_encode($data);

// Invocamos el servicio a ruc.com.pe
// Ejemplo para JSON
$ch = curl_init();
curl_setopt($ch, CURLOPT_URL, $ruta);
curl_setopt(
    $ch, CURLOPT_HTTPHEADER, array(
    'Content-Type: application/json',
    )
);
curl_setopt($ch, CURLOPT_POST, 1);
curl_setopt($ch, CURLOPT_SSL_VERIFYPEER, false);
curl_setopt($ch, CURLOPT_POSTFIELDS,$data_json);
curl_setopt($ch, CURLOPT_RETURNTRANSFER, true);
$respuesta  = curl_exec($ch);
curl_close($ch);

$array = json_decode($respuesta,true);
print_r($array);

Show me this array and I just want to capture the field [nombre_o_razon_social]

Array (
  [success] => 1
  [entity] => Array (
    [ruc] => 10486113532
    [nombre_o_razon_social] => GONZALES CHOCCATA FERNANDO ABEL
    [estado_del_contribuyente] => ACTIVO
    [condicion_de_domicilio] => HABIDO
    [ubigeo] => 080106
    [tipo_de_via] => CAL.
    [nombre_de_via] => TEQTE
    [codigo_de_zona] => -
    [tipo_de_zona] => -
    [numero] => 253
    [interior] => -
    [lote] => -
    [dpto] => -
    [manzana] => -
    [kilometro] => -
    [departamento] => CUSCO
    [provincia] => CUSCO
    [distrito] => SANTIAGO
    [direccion] => CAL. TEQTE NRO. 253
    [direccion_completa] => CAL. TEQTE NRO. 253 - CUSCO CUSCO SANTIAGO
    [ultima_actualizacion] => 2018-05-02 11:33:23
  )
)


print_r($array['nombre_o_razon_social']); 
Notice: Undefined index: nombre_o_razon_social in C:\xampp\htdocs\bb\consulta.php on line 33