856909694257 has 4 divisors (see below), whose sum is σ = 871433587440. Its totient is φ = 842385801076.

The previous prime is 856909694239. The next prime is 856909694261. The reversal of 856909694257 is 752496909658.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4.

It is a cyclic number.

It is not a de Polignac number, because 856909694257 - 2¹¹ = 856909692209 is a prime.

It is a super-2 number, since 2×856909694257² (a number of 25 digits) contains 22 as substring.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (856909694227) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 7261946503 + ... + 7261946620.

It is an arithmetic number, because the mean of its divisors is an integer number (217858396860).

Almost surely, 2^856909694257 is an apocalyptic number.

It is an amenable number.

856909694257 is a deficient number, since it is larger than the sum of its proper divisors (14523893183).

856909694257 is a wasteful number, since it uses less digits than its factorization.

856909694257 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 14523893182.

The product of its (nonzero) digits is 293932800, while the sum is 70.

The spelling of 856909694257 in words is "eight hundred fifty-six billion, nine hundred nine million, six hundred ninety-four thousand, two hundred fifty-seven".