681389 has 4 divisors (see below), whose sum is σ = 684480. Its totient is φ = 678300.

The previous prime is 681371. The next prime is 681403. The reversal of 681389 is 983186.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4, and also an emirpimes, since its reverse is a distinct semiprime: 983186 = 2 ⋅491593.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-681389 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (681089) 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, 1187 + ... + 1664.

It is an arithmetic number, because the mean of its divisors is an integer number (171120).

2⁶⁸¹³⁸⁹ is an apocalyptic number.

It is an amenable number.

681389 is a deficient number, since it is larger than the sum of its proper divisors (3091).

681389 is a wasteful number, since it uses less digits than its factorization.

681389 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 3090.

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

The square root of 681389 is about 825.4629004383. The cubic root of 681389 is about 87.9964271965.

The spelling of 681389 in words is "six hundred eighty-one thousand, three hundred eighty-nine".