686905831 has 4 divisors (see below), whose sum is σ = 686967232. Its totient is φ = 686844432.

The previous prime is 686905801. The next prime is 686905847. The reversal of 686905831 is 138509686.

It is a semiprime because it is the product of two primes, and also a brilliant number, because the two primes have the same length.

It is a cyclic number.

It is not a de Polignac number, because 686905831 - 2⁹ = 686905319 is a prime.

It is a super-2 number, since 2×686905831² = 943679241323601122, 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 (686905801) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 8631 + ... + 38056.

It is an arithmetic number, because the mean of its divisors is an integer number (171741808).

Almost surely, 2^686905831 is an apocalyptic number.

686905831 is a deficient number, since it is larger than the sum of its proper divisors (61401).

686905831 is a wasteful number, since it uses less digits than its factorization.

686905831 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 61400.

The product of its (nonzero) digits is 311040, while the sum is 46.

The square root of 686905831 is about 26208.8883968779. Note that the first 3 decimals coincide. The cubic root of 686905831 is about 882.3327531506.

The spelling of 686905831 in words is "six hundred eighty-six million, nine hundred five thousand, eight hundred thirty-one".