821138688 has 72 divisors (see below), whose sum is σ = 2428272000. Its totient is φ = 273710592.

The previous prime is 821138639. The next prime is 821138711. The reversal of 821138688 is 886831128.

It is a tau number, because it is divible by the number of its divisors (72).

It is a super-2 number, since 2×821138688² = 1348537489860722688, which contains 22 as substring.

It is a nude number because it is divisible by every one of its digits.

It is a congruent number.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 52488 + ... + 66311.

It is an arithmetic number, because the mean of its divisors is an integer number (33726000).

Almost surely, 2^821138688 is an apocalyptic number.

It is an amenable number.

821138688 is an abundant number, since it is smaller than the sum of its proper divisors (1607133312).

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

821138688 is a wasteful number, since it uses less digits than its factorization.

821138688 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 118824 (or 118804 counting only the distinct ones).

The product of its digits is 147456, while the sum is 45.

The square root of 821138688 is about 28655.5175838790. The cubic root of 821138688 is about 936.4232142682.

The spelling of 821138688 in words is "eight hundred twenty-one million, one hundred thirty-eight thousand, six hundred eighty-eight".