857686849 has 4 divisors (see below), whose sum is σ = 866178900. Its totient is φ = 849194800.

The previous prime is 857686807. The next prime is 857686853. The reversal of 857686849 is 948686758.

It is a semiprime because it is the product of two primes.

It can be written as a sum of positive squares in 2 ways, for example, as 816816400 + 40870449 = 28580^2 + 6393^2 .

It is a cyclic number.

It is not a de Polignac number, because 857686849 - 2⁹ = 857686337 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (857686549) 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, 4245874 + ... + 4246075.

It is an arithmetic number, because the mean of its divisors is an integer number (216544725).

Almost surely, 2^857686849 is an apocalyptic number.

It is an amenable number.

857686849 is a deficient number, since it is larger than the sum of its proper divisors (8492051).

857686849 is a wasteful number, since it uses less digits than its factorization.

857686849 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 8492050.

The product of its digits is 23224320, while the sum is 61.

The square root of 857686849 is about 29286.2911444928. The cubic root of 857686849 is about 950.1151657243.

Subtracting 857686849 from its reverse (948686758), we obtain a palindrome (90999909).

The spelling of 857686849 in words is "eight hundred fifty-seven million, six hundred eighty-six thousand, eight hundred forty-nine".