686573640 has 96 divisors (see below), whose sum is σ = 2237784120. Its totient is φ = 182559744.

The previous prime is 686573639. The next prime is 686573651. The reversal of 686573640 is 46375686.

It can be written as a sum of positive squares in 4 ways, for example, as 343509156 + 343064484 = 18534^2 + 18522^2 .

It is a Harshad number since it is a multiple of its sum of digits (45).

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 131724 + ... + 136836.

Almost surely, 2^686573640 is an apocalyptic number.

686573640 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 686573640, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (1118892060).

686573640 is an abundant number, since it is smaller than the sum of its proper divisors (1551210480).

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

686573640 is a wasteful number, since it uses less digits than its factorization.

686573640 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 5503 (or 5496 counting only the distinct ones).

The product of its (nonzero) digits is 725760, while the sum is 45.

The square root of 686573640 is about 26202.5502575608. The cubic root of 686573640 is about 882.1904967462.

The spelling of 686573640 in words is "six hundred eighty-six million, five hundred seventy-three thousand, six hundred forty".