681555840 has 512 divisors, whose sum is σ = 2784844800. Its totient is φ = 138018816.

The previous prime is 681555793. The next prime is 681555851. The reversal of 681555840 is 48555186.

681555840 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

It is a Harshad number since it is a multiple of its sum of digits (42).

It is a junction number, because it is equal to n+sod(n) for n = 681555792 and 681555801.

It is a congruent number.

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, 4341042 + ... + 4341198.

It is an arithmetic number, because the mean of its divisors is an integer number (5439150).

Almost surely, 2^681555840 is an apocalyptic number.

681555840 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 681555840, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (1392422400).

681555840 is an abundant number, since it is smaller than the sum of its proper divisors (2103288960).

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

681555840 is a wasteful number, since it uses less digits than its factorization.

681555840 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 222 (or 210 counting only the distinct ones).

The product of its (nonzero) digits is 192000, while the sum is 42.

The square root of 681555840 is about 26106.6244466802. The cubic root of 681555840 is about 880.0360866744.

The spelling of 681555840 in words is "six hundred eighty-one million, five hundred fifty-five thousand, eight hundred forty".