Deepsleep wake with remote GPIO to GPIO Pin

Projects Programming
1

Trying to externally wake a ESP32CAM off the master via this (pin 12)

digitalWrite(ledPin, HIGH);

this thread is getting me started.... unless there is a better way.

https://forum.arduino.cc/t/esp32-cam-pir-wakeup/575948/3

#define GPIO_PIN_WAKEUP GPIO_NUM_12
#define EXT_WAKEUP_PIN_BITMASK 0x1000  //  2^12
#define MINIMUM_WAKE_PERIOD_MILLIS 60e3

GPIO 12 but what does the next two lines mean?
4096?
Millis () is that value hex?

unsigned long secs() {
  return millis() / 1e3L;

Same again is that divide by the number in hex? Anyone point me to some references or explain please?

2

from school mathematics
1e3 = 1 * (10 in power 3) = 1000
60e3 = 60 * (10 in poer 3) = 60 000

thus
millis() / 1e3L = millis() /1000