681918 has 16 divisors (see below), whose sum is σ = 1380240. Its totient is φ = 224576.

The previous prime is 681913. The next prime is 681931. The reversal of 681918 is 819186.

It is a Curzon number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (681913) by changing a digit.

681918 is an untouchable number, because it is not equal to the sum of proper divisors of any number.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 105 + ... + 1172.

It is an arithmetic number, because the mean of its divisors is an integer number (86265).

2⁶⁸¹⁹¹⁸ is an apocalyptic number.

681918 is an abundant number, since it is smaller than the sum of its proper divisors (698322).

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

681918 is a wasteful number, since it uses less digits than its factorization.

681918 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1371.

The product of its digits is 3456, while the sum is 33.

The square root of 681918 is about 825.7832645434. The cubic root of 681918 is about 88.0191934719.

The spelling of 681918 in words is "six hundred eighty-one thousand, nine hundred eighteen".