681856 has 32 divisors (see below), whose sum is σ = 1554480. Its totient is φ = 291840.

The previous prime is 681841. The next prime is 681883. The reversal of 681856 is 658186.

It is a happy number.

It is a tau number, because it is divible by the number of its divisors (32).

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 516 + ... + 1276.

2⁶⁸¹⁸⁵⁶ 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 681856, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (777240).

681856 is an abundant number, since it is smaller than the sum of its proper divisors (872624).

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

681856 is an equidigital number, since it uses as much as digits as its factorization.

681856 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 782 (or 770 counting only the distinct ones).

The product of its digits is 11520, while the sum is 34.

The square root of 681856 is about 825.7457235735. The cubic root of 681856 is about 88.0165258220.

The spelling of 681856 in words is "six hundred eighty-one thousand, eight hundred fifty-six".