686881 has 4 divisors (see below), whose sum is σ = 739732. Its totient is φ = 634032.

The previous prime is 686879. The next prime is 686891. The reversal of 686881 is 188686.

686881 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 188686 = 2 ⋅94343.

It can be written as a sum of positive squares in 2 ways, for example, as 32400 + 654481 = 180^2 + 809^2 .

It is a cyclic number.

It is not a de Polignac number, because 686881 - 2¹ = 686879 is a prime.

It is a super-2 number, since 2×686881² = 943611016322, which contains 22 as substring.

It is a Duffinian number.

It is a self number, because there is not a number n which added to its sum of digits gives 686881.

It is not an unprimeable number, because it can be changed into a prime (686801) 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, 26406 + ... + 26431.

It is an arithmetic number, because the mean of its divisors is an integer number (184933).

2⁶⁸⁶⁸⁸¹ is an apocalyptic number.

It is an amenable number.

686881 is a deficient number, since it is larger than the sum of its proper divisors (52851).

686881 is a wasteful number, since it uses less digits than its factorization.

686881 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 52850.

The product of its digits is 18432, while the sum is 37.

The square root of 686881 is about 828.7828424865. The cubic root of 686881 is about 88.2322121189.

The spelling of 686881 in words is "six hundred eighty-six thousand, eight hundred eighty-one".