821865460 has 72 divisors (see below), whose sum is σ = 1911099960. Its totient is φ = 295128576.

The previous prime is 821865449. The next prime is 821865461. The reversal of 821865460 is 64568128.

It can be written as a sum of positive squares in 12 ways, for example, as 355216 + 821510244 = 596^2 + 28662^2 .

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (821865461) by changing a digit.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 354786 + ... + 357094.

It is an arithmetic number, because the mean of its divisors is an integer number (26543055).

Almost surely, 2^821865460 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 821865460, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (955549980).

821865460 is an abundant number, since it is smaller than the sum of its proper divisors (1089234500).

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

821865460 is a wasteful number, since it uses less digits than its factorization.

821865460 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 2405 (or 2366 counting only the distinct ones).

The product of its (nonzero) digits is 92160, while the sum is 40.

The square root of 821865460 is about 28668.1959669596. The cubic root of 821865460 is about 936.6994020775.

The spelling of 821865460 in words is "eight hundred twenty-one million, eight hundred sixty-five thousand, four hundred sixty".