821664722 has 6 divisors (see below), whose sum is σ = 1232557893. Its totient is φ = 410812092.

The previous prime is 821664691. The next prime is 821664773. The reversal of 821664722 is 227466128.

It can be written as a sum of positive squares in 2 ways, for example, as 755095441 + 66569281 = 27479^2 + 8159^2 .

It is an ABA number since it can be written as A⋅B^A, here for A=2, B=20269.

It is a Duffinian number.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written in 2 ways as a sum of consecutive naturals, for example, 30404 + ... + 50672.

Almost surely, 2^821664722 is an apocalyptic number.

821664722 is a deficient number, since it is larger than the sum of its proper divisors (410893171).

821664722 is an frugal number, since it uses more digits than its factorization.

821664722 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 40540 (or 20271 counting only the distinct ones).

The product of its digits is 64512, while the sum is 38.

The square root of 821664722 is about 28664.6946957403. The cubic root of 821664722 is about 936.6231339272.

The spelling of 821664722 in words is "eight hundred twenty-one million, six hundred sixty-four thousand, seven hundred twenty-two".