681989 has 16 divisors (see below), whose sum is σ = 902016. Its totient is φ = 499200.

The previous prime is 681983. The next prime is 681997. The reversal of 681989 is 989186.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-681989 is a prime.

It is a super-2 number, since 2×681989² = 930217992242, which contains 22 as substring.

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 (681983) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (7) of ones.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 1049 + ... + 1569.

It is an arithmetic number, because the mean of its divisors is an integer number (56376).

2⁶⁸¹⁹⁸⁹ is an apocalyptic number.

It is an amenable number.

681989 is a deficient number, since it is larger than the sum of its proper divisors (220027).

681989 is a wasteful number, since it uses less digits than its factorization.

681989 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 556.

The product of its digits is 31104, while the sum is 41.

The square root of 681989 is about 825.8262529128. The cubic root of 681989 is about 88.0222481626.

The spelling of 681989 in words is "six hundred eighty-one thousand, nine hundred eighty-nine".