1216808309 has 2 divisors, whose sum is σ = 1216808310. Its totient is φ = 1216808308.

The previous prime is 1216808287. The next prime is 1216808339. The reversal of 1216808309 is 9038086121.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 1202008900 + 14799409 = 34670^2 + 3847^2 .

It is an emirp because it is prime and its reverse (9038086121) is a distict prime.

It is a cyclic number.

It is not a de Polignac number, because 1216808309 - 2²⁰ = 1215759733 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (1216808339) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 608404154 + 608404155.

It is an arithmetic number, because the mean of its divisors is an integer number (608404155).

Almost surely, 2^1216808309 is an apocalyptic number.

It is an amenable number.

1216808309 is a deficient number, since it is larger than the sum of its proper divisors (1).

1216808309 is an equidigital number, since it uses as much as digits as its factorization.

1216808309 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 20736, while the sum is 38.

The square root of 1216808309 is about 34882.7795480807. The cubic root of 1216808309 is about 1067.5971085380.

The spelling of 1216808309 in words is "one billion, two hundred sixteen million, eight hundred eight thousand, three hundred nine".