821397885 has 128 divisors (see below), whose sum is σ = 1716940800. Its totient is φ = 325355520.

The previous prime is 821397883. The next prime is 821397887. The reversal of 821397885 is 588793128.

It is an interprime number because it is at equal distance from previous prime (821397883) and next prime (821397887).

It is not a de Polignac number, because 821397885 - 2¹ = 821397883 is a prime.

It is a Curzon number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (821397881) 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 127 ways as a sum of consecutive naturals, for example, 4588726 + ... + 4588904.

It is an arithmetic number, because the mean of its divisors is an integer number (13413600).

Almost surely, 2^821397885 is an apocalyptic number.

It is an amenable number.

821397885 is an abundant number, since it is smaller than the sum of its proper divisors (895542915).

It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.

821397885 is a wasteful number, since it uses less digits than its factorization.

821397885 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 371.

The product of its digits is 967680, while the sum is 51.

The square root of 821397885 is about 28660.0398638941. The cubic root of 821397885 is about 936.5217329705.

The spelling of 821397885 in words is "eight hundred twenty-one million, three hundred ninety-seven thousand, eight hundred eighty-five".