856212309 has 16 divisors (see below), whose sum is σ = 1269005440. Its totient is φ = 570564000.

The previous prime is 856212251. The next prime is 856212319. The reversal of 856212309 is 903212658.

856212309 is a `hidden beast` number, since 8 + 5 + 621 + 23 + 0 + 9 = 666.

It is not a de Polignac number, because 856212309 - 2¹¹ = 856210261 is a prime.

It is a super-2 number, since 2×856212309² = 1466199036166222962, which contains 22 as substring.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (856212319) 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 in 15 ways as a sum of consecutive naturals, for example, 75744 + ... + 86310.

It is an arithmetic number, because the mean of its divisors is an integer number (79312840).

Almost surely, 2^856212309 is an apocalyptic number.

It is an amenable number.

856212309 is a deficient number, since it is larger than the sum of its proper divisors (412793131).

856212309 is a wasteful number, since it uses less digits than its factorization.

856212309 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 13577 (or 13571 counting only the distinct ones).

The product of its (nonzero) digits is 25920, while the sum is 36.

The square root of 856212309 is about 29261.1057378220. The cubic root of 856212309 is about 949.5703723089.

The spelling of 856212309 in words is "eight hundred fifty-six million, two hundred twelve thousand, three hundred nine".