821022989 has 8 divisors (see below), whose sum is σ = 829159320. Its totient is φ = 812897856.

The previous prime is 821022971. The next prime is 821023009. The reversal of 821022989 is 989220128.

It can be written as a sum of positive squares in 4 ways, for example, as 241802500 + 579220489 = 15550^2 + 24067^2 .

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 821022989 - 2²⁴ = 804245773 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (821022959) 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, 292139 + ... + 294935.

It is an arithmetic number, because the mean of its divisors is an integer number (103644915).

Almost surely, 2^821022989 is an apocalyptic number.

It is an amenable number.

821022989 is a deficient number, since it is larger than the sum of its proper divisors (8136331).

821022989 is a wasteful number, since it uses less digits than its factorization.

821022989 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 5599.

The product of its (nonzero) digits is 41472, while the sum is 41.

The square root of 821022989 is about 28653.4987217966. The cubic root of 821022989 is about 936.3792313129.

The spelling of 821022989 in words is "eight hundred twenty-one million, twenty-two thousand, nine hundred eighty-nine".