681805728 has 192 divisors, whose sum is σ = 2146435200. Its totient is φ = 209848320.

The previous prime is 681805717. The next prime is 681805759. The reversal of 681805728 is 827508186.

681805728 is a `hidden beast` number, since 68 + 18 + 0 + 572 + 8 = 666.

It is an unprimeable number.

It is a polite number, since it can be written in 31 ways as a sum of consecutive naturals, for example, 672550 + ... + 673562.

It is an arithmetic number, because the mean of its divisors is an integer number (11179350).

Almost surely, 2^681805728 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 681805728, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (1073217600).

681805728 is an abundant number, since it is smaller than the sum of its proper divisors (1464629472).

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

681805728 is a wasteful number, since it uses less digits than its factorization.

681805728 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1092 (or 1078 counting only the distinct ones).

The product of its (nonzero) digits is 215040, while the sum is 45.

The square root of 681805728 is about 26111.4099198033. The cubic root of 681805728 is about 880.1436266948.

The spelling of 681805728 in words is "six hundred eighty-one million, eight hundred five thousand, seven hundred twenty-eight".