686442388 has 24 divisors (see below), whose sum is σ = 1275585192. Its totient is φ = 322105344.

The previous prime is 686442373. The next prime is 686442397. The reversal of 686442388 is 883244686.

It can be written as a sum of positive squares in 4 ways, for example, as 387774864 + 298667524 = 19692^2 + 17282^2 .

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 9706 + ... + 38302.

It is an arithmetic number, because the mean of its divisors is an integer number (53149383).

Almost surely, 2^686442388 is an apocalyptic number.

686442388 is a gapful number since it is divisible by the number (68) formed by its first and last digit.

It is an amenable number.

686442388 is a deficient number, since it is larger than the sum of its proper divisors (589142804).

686442388 is a wasteful number, since it uses less digits than its factorization.

686442388 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 28971 (or 28969 counting only the distinct ones).

The product of its digits is 1769472, while the sum is 49.

The square root of 686442388 is about 26200.0455724794. The cubic root of 686442388 is about 882.1342771656.

The spelling of 686442388 in words is "six hundred eighty-six million, four hundred forty-two thousand, three hundred eighty-eight".