821864880 has 240 divisors, whose sum is σ = 2909647104. Its totient is φ = 215550720.

The previous prime is 821864873. The next prime is 821864909. The reversal of 821864880 is 88468128.

It is a happy number.

821864880 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

It is a tau number, because it is divible by the number of its divisors (240).

It is a Harshad number since it is a multiple of its sum of digits (45).

It is an unprimeable number.

It is a polite number, since it can be written in 47 ways as a sum of consecutive naturals, for example, 1302165 + ... + 1302795.

Almost surely, 2^821864880 is an apocalyptic number.

821864880 is a gapful number since it is divisible by the number (80) formed by its first and last digit.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 821864880, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (1454823552).

821864880 is an abundant number, since it is smaller than the sum of its proper divisors (2087782224).

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

821864880 is a wasteful number, since it uses less digits than its factorization.

821864880 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 726 (or 708 counting only the distinct ones).

The product of its (nonzero) digits is 196608, while the sum is 45.

The square root of 821864880 is about 28668.1858512184. The cubic root of 821864880 is about 936.6991817309.

The spelling of 821864880 in words is "eight hundred twenty-one million, eight hundred sixty-four thousand, eight hundred eighty".