685899991 has 12 divisors (see below), whose sum is σ = 798319200. Its totient is φ = 587593440.

The previous prime is 685899961. The next prime is 685900013. The reversal of 685899991 is 199998586.

It is not a de Polignac number, because 685899991 - 2⁹ = 685899479 is a prime.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (685899911) by changing a digit.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 147106 + ... + 151696.

It is an arithmetic number, because the mean of its divisors is an integer number (66526600).

Almost surely, 2^685899991 is an apocalyptic number.

685899991 is a deficient number, since it is larger than the sum of its proper divisors (112419209).

685899991 is a wasteful number, since it uses less digits than its factorization.

685899991 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 7654 (or 7647 counting only the distinct ones).

The product of its digits is 12597120, while the sum is 64.

The square root of 685899991 is about 26189.6924571481. The cubic root of 685899991 is about 881.9018745292.

The spelling of 685899991 in words is "six hundred eighty-five million, eight hundred ninety-nine thousand, nine hundred ninety-one".