16855309 has 2 divisors, whose sum is σ = 16855310. Its totient is φ = 16855308.

The previous prime is 16855303. The next prime is 16855331. The reversal of 16855309 is 90355861.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 10989225 + 5866084 = 3315^2 + 2422^2 .

It is an emirp because it is prime and its reverse (90355861) is a distict prime.

It is a cyclic number.

It is not a de Polignac number, because 16855309 - 2⁵ = 16855277 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (16855303) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 8427654 + 8427655.

It is an arithmetic number, because the mean of its divisors is an integer number (8427655).

Almost surely, 2^16855309 is an apocalyptic number.

It is an amenable number.

16855309 is a deficient number, since it is larger than the sum of its proper divisors (1).

16855309 is an equidigital number, since it uses as much as digits as its factorization.

16855309 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 32400, while the sum is 37.

The square root of 16855309 is about 4105.5217695197. The cubic root of 16855309 is about 256.3965868414.

The spelling of 16855309 in words is "sixteen million, eight hundred fifty-five thousand, three hundred nine".