821028660 has 72 divisors (see below), whose sum is σ = 2339099616. Its totient is φ = 215175360.

The previous prime is 821028643. The next prime is 821028673. The reversal of 821028660 is 66820128.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 206895 + ... + 210825.

Almost surely, 2^821028660 is an apocalyptic number.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 821028660, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (1169549808).

821028660 is an abundant number, since it is smaller than the sum of its proper divisors (1518070956).

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

821028660 is a wasteful number, since it uses less digits than its factorization.

821028660 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 4061 (or 4000 counting only the distinct ones).

The product of its (nonzero) digits is 9216, while the sum is 33.

The square root of 821028660 is about 28653.5976798726. The cubic root of 821028660 is about 936.3813872389.

Adding to 821028660 its reverse (66820128), we get a palindrome (887848788).

The spelling of 821028660 in words is "eight hundred twenty-one million, twenty-eight thousand, six hundred sixty".