681599840 has 48 divisors (see below), whose sum is σ = 1616077008. Its totient is φ = 271658496.

The previous prime is 681599839. The next prime is 681599851. The reversal of 681599840 is 48995186.

It is a happy number.

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, 37754 + ... + 52806.

It is an arithmetic number, because the mean of its divisors is an integer number (33668271).

Almost surely, 2^681599840 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 681599840, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (808038504).

681599840 is an abundant number, since it is smaller than the sum of its proper divisors (934477168).

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

681599840 is a wasteful number, since it uses less digits than its factorization.

681599840 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 15351 (or 15343 counting only the distinct ones).

The product of its (nonzero) digits is 622080, while the sum is 50.

The square root of 681599840 is about 26107.4671310719. The cubic root of 681599840 is about 880.0550241076.

The spelling of 681599840 in words is "six hundred eighty-one million, five hundred ninety-nine thousand, eight hundred forty".