821560 has 64 divisors (see below), whose sum is σ = 2073600. Its totient is φ = 291456.

The previous prime is 821551. The next prime is 821573. The reversal of 821560 is 65128.

It is a happy number.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 17457 + ... + 17503.

It is an arithmetic number, because the mean of its divisors is an integer number (32400).

2⁸²¹⁵⁶⁰ 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 821560, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (1036800).

821560 is an abundant number, since it is smaller than the sum of its proper divisors (1252040).

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

821560 is a wasteful number, since it uses less digits than its factorization.

821560 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 100 (or 96 counting only the distinct ones).

The product of its (nonzero) digits is 480, while the sum is 22.

The square root of 821560 is about 906.3994704323. The cubic root of 821560 is about 93.6583341048.

Adding to 821560 its reverse (65128), we get a palindrome (886688).

The spelling of 821560 in words is "eight hundred twenty-one thousand, five hundred sixty".