1216765709 has 2 divisors, whose sum is σ = 1216765710. Its totient is φ = 1216765708.

The previous prime is 1216765639. The next prime is 1216765723. The reversal of 1216765709 is 9075676121.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 1053002500 + 163763209 = 32450^2 + 12797^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-1216765709 is a prime.

It is a super-3 number, since 3×1216765709³ (a number of 28 digits) contains 333 as substring.

It is a self number, because there is not a number n which added to its sum of digits gives 1216765709.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (1216725709) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 608382854 + 608382855.

It is an arithmetic number, because the mean of its divisors is an integer number (608382855).

Almost surely, 2^1216765709 is an apocalyptic number.

It is an amenable number.

1216765709 is a deficient number, since it is larger than the sum of its proper divisors (1).

1216765709 is an equidigital number, since it uses as much as digits as its factorization.

1216765709 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 158760, while the sum is 44.

The square root of 1216765709 is about 34882.1689262580. The cubic root of 1216765709 is about 1067.5846496686.

The spelling of 1216765709 in words is "one billion, two hundred sixteen million, seven hundred sixty-five thousand, seven hundred nine".