686605731840 has 768 divisors, whose sum is σ = 2809235520000. Its totient is φ = 155819704320.

The previous prime is 686605731821. The next prime is 686605731863. The reversal of 686605731840 is 48137506686.

686605731840 is a `hidden beast` number, since 6 + 8 + 6 + 60 + 573 + 1 + 8 + 4 + 0 = 666.

It is a tau number, because it is divible by the number of its divisors (768).

It is a Harshad number since it is a multiple of its sum of digits (54).

It is an unprimeable number.

It is a polite number, since it can be written in 63 ways as a sum of consecutive naturals, for example, 288367450 + ... + 288369830.

It is an arithmetic number, because the mean of its divisors is an integer number (3657858750).

Almost surely, 2^686605731840 is an apocalyptic number.

686605731840 is a gapful number since it is divisible by the number (60) formed by its first and last digit.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 686605731840, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (1404617760000).

686605731840 is an abundant number, since it is smaller than the sum of its proper divisors (2122629788160).

It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.

686605731840 is a wasteful number, since it uses less digits than its factorization.

686605731840 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 2573 (or 2547 counting only the distinct ones).

The product of its (nonzero) digits is 5806080, while the sum is 54.

The spelling of 686605731840 in words is "six hundred eighty-six billion, six hundred five million, seven hundred thirty-one thousand, eight hundred forty".