687685 has 4 divisors (see below), whose sum is σ = 825228. Its totient is φ = 550144.

The previous prime is 687683. The next prime is 687691. The reversal of 687685 is 586786.

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 431649 + 256036 = 657^2 + 506^2 .

It is a cyclic number.

It is not a de Polignac number, because 687685 - 2¹ = 687683 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (687683) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 68764 + ... + 68773.

It is an arithmetic number, because the mean of its divisors is an integer number (206307).

2⁶⁸⁷⁶⁸⁵ is an apocalyptic number.

It is an amenable number.

687685 is a deficient number, since it is larger than the sum of its proper divisors (137543).

687685 is a wasteful number, since it uses less digits than its factorization.

687685 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 137542.

The product of its digits is 80640, while the sum is 40.

The square root of 687685 is about 829.2677492825. The cubic root of 687685 is about 88.2666242119.

The spelling of 687685 in words is "six hundred eighty-seven thousand, six hundred eighty-five".