809681 has 4 divisors (see below), whose sum is σ = 825012. Its totient is φ = 794352.

The previous prime is 809629. The next prime is 809701. The reversal of 809681 is 186908.

809681 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

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 297025 + 512656 = 545^2 + 716^2 .

It is a cyclic number.

It is not a de Polignac number, because 809681 - 2¹⁴ = 793297 is a prime.

It is a super-2 number, since 2×809681² = 1311166643522, which contains 22 as substring.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (809581) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 7586 + ... + 7691.

It is an arithmetic number, because the mean of its divisors is an integer number (206253).

2⁸⁰⁹⁶⁸¹ is an apocalyptic number.

It is an amenable number.

809681 is a deficient number, since it is larger than the sum of its proper divisors (15331).

809681 is a wasteful number, since it uses less digits than its factorization.

809681 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 15330.

The product of its (nonzero) digits is 3456, while the sum is 32.

The square root of 809681 is about 899.8227603256. The cubic root of 809681 is about 93.2047364463.

The spelling of 809681 in words is "eight hundred nine thousand, six hundred eighty-one".