686660724 has 54 divisors (see below), whose sum is σ = 1797795090. Its totient is φ = 220721760.

The previous prime is 686660717. The next prime is 686660749. The reversal of 686660724 is 427066686.

It can be written as a sum of positive squares in only one way, i.e., 591948900 + 94711824 = 24330^2 + 9732^2 .

It is a self number, because there is not a number n which added to its sum of digits gives 686660724.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 17 ways as a sum of consecutive naturals, for example, 846279 + ... + 847089.

Almost surely, 2^686660724 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 686660724, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (898897545).

686660724 is an abundant number, since it is smaller than the sum of its proper divisors (1111134366).

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

686660724 is a wasteful number, since it uses less digits than its factorization.

686660724 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1661 (or 845 counting only the distinct ones).

The product of its (nonzero) digits is 580608, while the sum is 45.

The square root of 686660724 is about 26204.2119515165. The cubic root of 686660724 is about 882.2277937550.

The spelling of 686660724 in words is "six hundred eighty-six million, six hundred sixty thousand, seven hundred twenty-four".