681840 has 60 divisors (see below), whose sum is σ = 2292264. Its totient is φ = 181632.

The previous prime is 681839. The next prime is 681841. The reversal of 681840 is 48186.

681840 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

It is an interprime number because it is at equal distance from previous prime (681839) and next prime (681841).

It is a tau number, because it is divible by the number of its divisors (60).

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (681841) by changing a digit.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 247 + ... + 1193.

2⁶⁸¹⁸⁴⁰ is an apocalyptic number.

681840 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 681840, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (1146132).

681840 is an abundant number, since it is smaller than the sum of its proper divisors (1610424).

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

681840 is a wasteful number, since it uses less digits than its factorization.

681840 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 966 (or 957 counting only the distinct ones).

The product of its (nonzero) digits is 1536, while the sum is 27.

The square root of 681840 is about 825.7360353043. The cubic root of 681840 is about 88.0158373700.

It can be divided in two parts, 681 and 840, that added together give a square (1521 = 39²).

The spelling of 681840 in words is "six hundred eighty-one thousand, eight hundred forty".