821808973 has 2 divisors, whose sum is σ = 821808974. Its totient is φ = 821808972.

The previous prime is 821808877. The next prime is 821809003. The reversal of 821808973 is 379808128.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 518108644 + 303700329 = 22762^2 + 17427^2 .

It is a cyclic number.

It is not a de Polignac number, because 821808973 - 2²⁹ = 284938061 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (821808773) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (19) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 410904486 + 410904487.

It is an arithmetic number, because the mean of its divisors is an integer number (410904487).

Almost surely, 2^821808973 is an apocalyptic number.

It is an amenable number.

821808973 is a deficient number, since it is larger than the sum of its proper divisors (1).

821808973 is an equidigital number, since it uses as much as digits as its factorization.

821808973 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 193536, while the sum is 46.

The square root of 821808973 is about 28667.2107642163. The cubic root of 821808973 is about 936.6779417315.

The spelling of 821808973 in words is "eight hundred twenty-one million, eight hundred eight thousand, nine hundred seventy-three".