809021 has 4 divisors (see below), whose sum is σ = 814332. Its totient is φ = 803712.

The previous prime is 808993. The next prime is 809023. The reversal of 809021 is 120908.

809021 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 372100 + 436921 = 610^2 + 661^2 .

It is a cyclic number.

It is not a de Polignac number, because 809021 - 2⁶ = 808957 is a prime.

It is a Duffinian number.

It is a junction number, because it is equal to n+sod(n) for n = 808984 and 809002.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (809023) 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, 2420 + ... + 2733.

It is an arithmetic number, because the mean of its divisors is an integer number (203583).

2⁸⁰⁹⁰²¹ is an apocalyptic number.

It is an amenable number.

809021 is a deficient number, since it is larger than the sum of its proper divisors (5311).

809021 is a wasteful number, since it uses less digits than its factorization.

809021 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 5310.

The product of its (nonzero) digits is 144, while the sum is 20.

The square root of 809021 is about 899.4559466700. The cubic root of 809021 is about 93.1794047218.

Adding to 809021 its reverse (120908), we get a palindrome (929929).

The spelling of 809021 in words is "eight hundred nine thousand, twenty-one".