681904 has 40 divisors (see below), whose sum is σ = 1473120. Its totient is φ = 304128.

The previous prime is 681899. The next prime is 681913. The reversal of 681904 is 409186.

681904 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

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, 6202 + ... + 6310.

It is an arithmetic number, because the mean of its divisors is an integer number (36828).

2⁶⁸¹⁹⁰⁴ 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 681904, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (736560).

681904 is an abundant number, since it is smaller than the sum of its proper divisors (791216).

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

681904 is a wasteful number, since it uses less digits than its factorization.

681904 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 157 (or 151 counting only the distinct ones).

The product of its (nonzero) digits is 1728, while the sum is 28.

The square root of 681904 is about 825.7747876994. The cubic root of 681904 is about 88.0185911134.

The spelling of 681904 in words is "six hundred eighty-one thousand, nine hundred four".