129216509 has 2 divisors, whose sum is σ = 129216510. Its totient is φ = 129216508.

The previous prime is 129216499. The next prime is 129216551. The reversal of 129216509 is 905612921.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 74011609 + 55204900 = 8603^2 + 7430^2 .

It is an emirp because it is prime and its reverse (905612921) is a distict prime.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-129216509 is a prime.

It is a Chen prime.

It is an alternating number because its digits alternate between odd and even.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (129216559) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 64608254 + 64608255.

It is an arithmetic number, because the mean of its divisors is an integer number (64608255).

Almost surely, 2^129216509 is an apocalyptic number.

It is an amenable number.

129216509 is a deficient number, since it is larger than the sum of its proper divisors (1).

129216509 is an equidigital number, since it uses as much as digits as its factorization.

129216509 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 9720, while the sum is 35.

The square root of 129216509 is about 11367.3439729780. The cubic root of 129216509 is about 505.5599565978.

The spelling of 129216509 in words is "one hundred twenty-nine million, two hundred sixteen thousand, five hundred nine".