865821440628 has 84 divisors (see below), whose sum is σ = 2281249091520. Its totient is φ = 287399354256.

The previous prime is 865821440587. The next prime is 865821440681. The reversal of 865821440628 is 826044128568.

865821440628 is a `hidden beast` number, since 8 + 6 + 5 + 8 + 2 + 1 + 4 + 4 + 0 + 628 = 666.

It is a super-2 number, since 2×865821440628² (a number of 25 digits) contains 22 as substring.

It is a Harshad number since it is a multiple of its sum of digits (54).

It is a congruent number.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (23) of ones.

It is a polite number, since it can be written in 27 ways as a sum of consecutive naturals, for example, 75751 + ... + 1318097.

It is an arithmetic number, because the mean of its divisors is an integer number (27157727280).

Almost surely, 2^865821440628 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 865821440628, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (1140624545760).

865821440628 is an abundant number, since it is smaller than the sum of its proper divisors (1415427650892).

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

865821440628 is a wasteful number, since it uses less digits than its factorization.

865821440628 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1242608 (or 1242591 counting only the distinct ones).

The product of its (nonzero) digits is 5898240, while the sum is 54.

It can be divided in two parts, 865821 and 440628, that added together give a square (1306449 = 1143²).

The spelling of 865821440628 in words is "eight hundred sixty-five billion, eight hundred twenty-one million, four hundred forty thousand, six hundred twenty-eight".