681893 has 4 divisors (see below), whose sum is σ = 691308. Its totient is φ = 672480.

The previous prime is 681883. The next prime is 681899. The reversal of 681893 is 398186.

It is a semiprime because it is the product of two primes.

It can be written as a sum of positive squares in 2 ways, for example, as 293764 + 388129 = 542^2 + 623^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-681893 is a prime.

It is an Ulam number.

It is a Duffinian number.

It is a Curzon number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (681899) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 4598 + ... + 4743.

It is an arithmetic number, because the mean of its divisors is an integer number (172827).

2⁶⁸¹⁸⁹³ is an apocalyptic number.

It is an amenable number.

681893 is a deficient number, since it is larger than the sum of its proper divisors (9415).

681893 is an equidigital number, since it uses as much as digits as its factorization.

681893 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 9414.

The product of its digits is 10368, while the sum is 35.

The square root of 681893 is about 825.7681272609. The cubic root of 681893 is about 88.0181178260.

The spelling of 681893 in words is "six hundred eighty-one thousand, eight hundred ninety-three".