821197920 has 192 divisors, whose sum is σ = 2760682176. Its totient is φ = 204472320.

The previous prime is 821197907. The next prime is 821197963. The reversal of 821197920 is 29791128.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 31 ways as a sum of consecutive naturals, for example, 1280800 + ... + 1281440.

It is an arithmetic number, because the mean of its divisors is an integer number (14378553).

Almost surely, 2^821197920 is an apocalyptic number.

821197920 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 821197920, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (1380341088).

821197920 is an abundant number, since it is smaller than the sum of its proper divisors (1939484256).

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

821197920 is a wasteful number, since it uses less digits than its factorization.

821197920 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 833 (or 825 counting only the distinct ones).

The product of its (nonzero) digits is 18144, while the sum is 39.

The square root of 821197920 is about 28656.5510834783. The cubic root of 821197920 is about 936.4457297039.

The spelling of 821197920 in words is "eight hundred twenty-one million, one hundred ninety-seven thousand, nine hundred twenty".