809812021 has 8 divisors (see below), whose sum is σ = 827443584. Its totient is φ = 792197280.

The previous prime is 809811997. The next prime is 809812043. The reversal of 809812021 is 120218908.

It is a happy number.

It is a sphenic number, since it is the product of 3 distinct primes.

It is a cyclic number.

It is not a de Polignac number, because 809812021 - 2²⁵ = 776257589 is a prime.

It is a super-2 number, since 2×809812021² = 1311591018712208882, which contains 22 as substring.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (809812061) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 170286 + ... + 174976.

It is an arithmetic number, because the mean of its divisors is an integer number (103430448).

Almost surely, 2^809812021 is an apocalyptic number.

It is an amenable number.

809812021 is a deficient number, since it is larger than the sum of its proper divisors (17631563).

809812021 is a wasteful number, since it uses less digits than its factorization.

809812021 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 8411.

The product of its (nonzero) digits is 2304, while the sum is 31.

The square root of 809812021 is about 28457.1962954891. The cubic root of 809812021 is about 932.0976357801.

The spelling of 809812021 in words is "eight hundred nine million, eight hundred twelve thousand, twenty-one".