681839 has 2 divisors, whose sum is σ = 681840. Its totient is φ = 681838.

The previous prime is 681833. The next prime is 681841. The reversal of 681839 is 938186.

It is a strong prime.

It is a cyclic number.

It is not a de Polignac number, because 681839 - 2⁴ = 681823 is a prime.

It is a Sophie Germain prime.

Together with 681841, it forms a pair of twin primes.

It is a Chen prime.

It is a junction number, because it is equal to n+sod(n) for n = 681799 and 681808.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (681833) by changing a digit.

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 as a sum of consecutive naturals, namely, 340919 + 340920.

It is an arithmetic number, because the mean of its divisors is an integer number (340920).

2⁶⁸¹⁸³⁹ is an apocalyptic number.

681839 is a deficient number, since it is larger than the sum of its proper divisors (1).

681839 is an equidigital number, since it uses as much as digits as its factorization.

681839 is an odious number, because the sum of its binary digits is odd.

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

The square root of 681839 is about 825.7354297837. The cubic root of 681839 is about 88.0157943414.

The spelling of 681839 in words is "six hundred eighty-one thousand, eight hundred thirty-nine".