821023009 has 2 divisors, whose sum is σ = 821023010. Its totient is φ = 821023008.

The previous prime is 821022971. The next prime is 821023033. The reversal of 821023009 is 900320128.

821023009 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 477291409 + 343731600 = 21847^2 + 18540^2 .

It is a cyclic number.

It is not a de Polignac number, because 821023009 - 2¹⁵ = 820990241 is a prime.

It is not a weakly prime, because it can be changed into another prime (821023909) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 410511504 + 410511505.

It is an arithmetic number, because the mean of its divisors is an integer number (410511505).

Almost surely, 2^821023009 is an apocalyptic number.

It is an amenable number.

821023009 is a deficient number, since it is larger than the sum of its proper divisors (1).

821023009 is an equidigital number, since it uses as much as digits as its factorization.

821023009 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 864, while the sum is 25.

The square root of 821023009 is about 28653.4990707941. The cubic root of 821023009 is about 936.3792389163.

The spelling of 821023009 in words is "eight hundred twenty-one million, twenty-three thousand, nine".