Attiny85 timer1 interrupt wakeup

Other Hardware 3rd Party Boards
1

Hello,
I want to achieve that after every 11minutes the Attiny wakes up, puts LED on and then repeat the same procedure after 11minutes. I want to save power, turning off all the other appliences as it is running on CR2032. Processor clock is running on 1Mhz.
Is the code snippet working?

2 
type or paste code here

/*
/* * Program ATTiny85 to blink LED connected to PB1 at 1s interval.
 * Assumes ATTiny85 is running at 1MHz internal clock speed.
 */

#include <avr/io.h>
#include <avr/wdt.h>
#include <avr/sleep.h>
#include <avr/interrupt.h>

bool timer1 = false, led = true;


// Interrupt service routine for timer1
ISR(TIMER1_COMPA_vect)
{
  timer1 = true;
}

void setup() {

  // Setup output pins
  pinMode(1, OUTPUT);
  digitalWrite(1, led);
  set_sleep_mode(SLEEP_MODE_IDLE);

  // Setup timer1 to interrupt every second
  TCCR1 = 0; // Stop timer
  TCNT1 = 0; // Zero timer
  GTCCR = _BV(PSR1); // Reset prescaler
  OCR1A = 660000000; // T = prescaler / 1MHz = 0.004096s; OCR1A = (1s/T) - 1 = 243 //1min @1Mhz
  OCR1C = 660000000; // Set to same value to reset timer1 to 0 after a compare match
  TIMSK = _BV(OCIE1A); // Interrupt on compare match with OCR1A
  
  // Start timer in CTC mode; prescaler = 4096; 
  TCCR1 = _BV(CTC1) | _BV(CS13) | _BV(CS12) | _BV(CS10);
  sei();
}

void loop() {
  if (timer1) {
    timer1 = false;
    led = !led;
    digitalWrite(1, led);
  }
  sleep_enable();
  sleep_cpu(); // CPU goes to sleep here; will be woken up by timer1 interrupt
}
3

That won't work. OCR1A and OCR1C are 8bit registers, a value 660 Mio. won't fit into one byte.