809121021 has 8 divisors (see below), whose sum is σ = 1081834560. Its totient is φ = 537910752.

The previous prime is 809121017. The next prime is 809121029. The reversal of 809121021 is 120121908.

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

It is not a de Polignac number, because 809121021 - 2² = 809121017 is a prime.

It is a junction number, because it is equal to n+sod(n) for n = 809120982 and 809121000.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (809121029) 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, 374560 + ... + 376713.

It is an arithmetic number, because the mean of its divisors is an integer number (135229320).

Almost surely, 2^809121021 is an apocalyptic number.

It is an amenable number.

809121021 is a deficient number, since it is larger than the sum of its proper divisors (272713539).

809121021 is a wasteful number, since it uses less digits than its factorization.

809121021 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 751635.

The product of its (nonzero) digits is 288, while the sum is 24.

The square root of 809121021 is about 28445.0526629852. The cubic root of 809121021 is about 931.8324455339.

Adding to 809121021 its reverse (120121908), we get a palindrome (929242929).

The spelling of 809121021 in words is "eight hundred nine million, one hundred twenty-one thousand, twenty-one".