686820689 has 4 divisors (see below), whose sum is σ = 727221924. Its totient is φ = 646419456.

The previous prime is 686820679. The next prime is 686820691. The reversal of 686820689 is 986028686.

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 547934464 + 138886225 = 23408^2 + 11785^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-686820689 is a prime.

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 686820689.

It is not an unprimeable number, because it can be changed into a prime (686820619) 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, 20200592 + ... + 20200625.

It is an arithmetic number, because the mean of its divisors is an integer number (181805481).

Almost surely, 2^686820689 is an apocalyptic number.

It is an amenable number.

686820689 is a deficient number, since it is larger than the sum of its proper divisors (40401235).

686820689 is a wasteful number, since it uses less digits than its factorization.

686820689 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 40401234.

The product of its (nonzero) digits is 1990656, while the sum is 53.

The square root of 686820689 is about 26207.2640502590. The cubic root of 686820689 is about 882.2962965865.

The spelling of 686820689 in words is "six hundred eighty-six million, eight hundred twenty thousand, six hundred eighty-nine".