821628889 has 8 divisors (see below), whose sum is σ = 842100840. Its totient is φ = 801177600.

The previous prime is 821628881. The next prime is 821628893. The reversal of 821628889 is 988826128.

It can be written as a sum of positive squares in 4 ways, for example, as 33872400 + 787756489 = 5820^2 + 28067^2 .

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 821628889 - 2³ = 821628881 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (821628881) by changing a digit.

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 7 ways as a sum of consecutive naturals, for example, 103129 + ... + 110809.

It is an arithmetic number, because the mean of its divisors is an integer number (105262605).

Almost surely, 2^821628889 is an apocalyptic number.

It is an amenable number.

821628889 is a deficient number, since it is larger than the sum of its proper divisors (20471951).

821628889 is a wasteful number, since it uses less digits than its factorization.

821628889 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 10331.

The product of its digits is 884736, while the sum is 52.

The square root of 821628889 is about 28664.0696517435. The cubic root of 821628889 is about 936.6095182744.

The spelling of 821628889 in words is "eight hundred twenty-one million, six hundred twenty-eight thousand, eight hundred eighty-nine".