857821440 has 432 divisors, whose sum is σ = 3288321792. Its totient is φ = 189923328.

The previous prime is 857821397. The next prime is 857821441. The reversal of 857821440 is 44128758.

It is a happy number.

It is a super-3 number, since 3×857821440³ (a number of 28 digits) contains 333 as substring.

It is not an unprimeable number, because it can be changed into a prime (857821441) by changing a digit.

It is a polite number, since it can be written in 47 ways as a sum of consecutive naturals, for example, 8843472 + ... + 8843568.

It is an arithmetic number, because the mean of its divisors is an integer number (7611856).

Almost surely, 2^857821440 is an apocalyptic number.

857821440 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 857821440, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (1644160896).

857821440 is an abundant number, since it is smaller than the sum of its proper divisors (2430500352).

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

857821440 is a wasteful number, since it uses less digits than its factorization.

857821440 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 182 (or 161 counting only the distinct ones).

The product of its (nonzero) digits is 71680, while the sum is 39.

The square root of 857821440 is about 29288.5889042132. The cubic root of 857821440 is about 950.1648615086.

The spelling of 857821440 in words is "eight hundred fifty-seven million, eight hundred twenty-one thousand, four hundred forty".