686690784 has 144 divisors (see below), whose sum is σ = 2181200112. Its totient is φ = 211258368.

The previous prime is 686690777. The next prime is 686690857. The reversal of 686690784 is 487096686.

It is a tau number, because it is divible by the number of its divisors (144).

It is a Smith number, since the sum of its digits (54) coincides with the sum of the digits of its prime factors.

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

It is a self number, because there is not a number n which added to its sum of digits gives 686690784.

It is a congruent number.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 97692 + ... + 104484.

It is an arithmetic number, because the mean of its divisors is an integer number (15147223).

Almost surely, 2^686690784 is an apocalyptic number.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 686690784, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (1090600056).

686690784 is an abundant number, since it is smaller than the sum of its proper divisors (1494509328).

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

686690784 is a wasteful number, since it uses less digits than its factorization.

686690784 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 6831 (or 6811 counting only the distinct ones).

The product of its (nonzero) digits is 3483648, while the sum is 54.

The square root of 686690784 is about 26204.7855171532. The cubic root of 686690784 is about 882.2406673521.

The spelling of 686690784 in words is "six hundred eighty-six million, six hundred ninety thousand, seven hundred eighty-four".