685561639 has 8 divisors (see below), whose sum is σ = 791257248. Its totient is φ = 581805600.

The previous prime is 685561619. The next prime is 685561661. The reversal of 685561639 is 936165586.

It is a happy number.

It is a sphenic number, since it is the product of 3 distinct primes.

It is a cyclic number.

It is not a de Polignac number, because 685561639 - 2⁵ = 685561607 is a prime.

It is a Duffinian number.

It is a junction number, because it is equal to n+sod(n) for n = 685561592 and 685561601.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (685561619) 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 7 ways as a sum of consecutive naturals, for example, 484132 + ... + 485545.

It is an arithmetic number, because the mean of its divisors is an integer number (98907156).

Almost surely, 2^685561639 is an apocalyptic number.

685561639 is a deficient number, since it is larger than the sum of its proper divisors (105695609).

685561639 is a wasteful number, since it uses less digits than its factorization.

685561639 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 969785.

The product of its digits is 1166400, while the sum is 49.

The square root of 685561639 is about 26183.2320197488. The cubic root of 685561639 is about 881.7568376696.

The spelling of 685561639 in words is "six hundred eighty-five million, five hundred sixty-one thousand, six hundred thirty-nine".