681440 has 24 divisors (see below), whose sum is σ = 1610280. Its totient is φ = 272512.

The previous prime is 681427. The next prime is 681449. The reversal of 681440 is 44186.

It is a happy number.

It is a congruent number.

It is an inconsummate number, since it does not exist a number n which divided by its sum of digits gives 681440.

It is not an unprimeable number, because it can be changed into a prime (681449) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 1970 + ... + 2289.

It is an arithmetic number, because the mean of its divisors is an integer number (67095).

2⁶⁸¹⁴⁴⁰ is an apocalyptic number.

It is an amenable number.

681440 is an abundant number, since it is smaller than the sum of its proper divisors (928840).

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

681440 is a wasteful number, since it uses less digits than its factorization.

681440 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 4274 (or 4266 counting only the distinct ones).

The product of its (nonzero) digits is 768, while the sum is 23.

The square root of 681440 is about 825.4937916181. The cubic root of 681440 is about 87.9986225680.

The spelling of 681440 in words is "six hundred eighty-one thousand, four hundred forty".