686806849 has 9 divisors (see below), whose sum is σ = 698289123. Its totient is φ = 675511632.

The previous prime is 686806801. The next prime is 686806871. The reversal of 686806849 is 948608686.

It is a happy number.

The square root of 686806849 is 26207.

It is a perfect power (a square), and thus also a powerful number.

It can be written as a sum of positive squares in only one way, i.e., 389865025 + 296941824 = 19745^2 + 17232^2 .

It is not a de Polignac number, because 686806849 - 2⁷ = 686806721 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 686806849.

It is not an unprimeable number, because it can be changed into a prime (686806049) 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 8 ways as a sum of consecutive naturals, for example, 1912932 + ... + 1913290.

Almost surely, 2^686806849 is an apocalyptic number.

686806849 is the 26207-th square number.

686806849 is the 13104-th centered octagonal number.

It is an amenable number.

686806849 is a deficient number, since it is larger than the sum of its proper divisors (11482274).

686806849 is an frugal number, since it uses more digits than its factorization.

686806849 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 864 (or 432 counting only the distinct ones).

The product of its (nonzero) digits is 3981312, while the sum is 55.

The cubic root of 686806849 is about 882.2903702154.

The spelling of 686806849 in words is "six hundred eighty-six million, eight hundred six thousand, eight hundred forty-nine".