821022720 has 416 divisors, whose sum is σ = 3170506752. Its totient is φ = 177340416.

The previous prime is 821022707. The next prime is 821022721. The reversal of 821022720 is 27220128.

It is a happy number.

It is a Harshad number since it is a multiple of its sum of digits (24).

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (821022721) by changing a digit.

It is a polite number, since it can be written in 31 ways as a sum of consecutive naturals, for example, 9891799 + ... + 9891881.

Almost surely, 2^821022720 is an apocalyptic number.

821022720 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 821022720, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (1585253376).

821022720 is an abundant number, since it is smaller than the sum of its proper divisors (2349484032).

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

821022720 is a wasteful number, since it uses less digits than its factorization.

821022720 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 145 (or 123 counting only the distinct ones).

The product of its (nonzero) digits is 896, while the sum is 24.

The square root of 821022720 is about 28653.4940277796. The cubic root of 821022720 is about 936.3791290478.

Adding to 821022720 its reverse (27220128), we get a palindrome (848242848).

The spelling of 821022720 in words is "eight hundred twenty-one million, twenty-two thousand, seven hundred twenty".