861857840 has 160 divisors (see below), whose sum is σ = 2256284160. Its totient is φ = 304443392.

The previous prime is 861857833. The next prime is 861857849. The reversal of 861857840 is 48758168.

It is a happy number.

861857840 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

It is not an unprimeable number, because it can be changed into a prime (861857849) by changing a digit.

It is a polite number, since it can be written in 31 ways as a sum of consecutive naturals, for example, 1845287 + ... + 1845753.

It is an arithmetic number, because the mean of its divisors is an integer number (14101776).

Almost surely, 2^861857840 is an apocalyptic number.

861857840 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 861857840, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (1128142080).

861857840 is an abundant number, since it is smaller than the sum of its proper divisors (1394426320).

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

861857840 is a wasteful number, since it uses less digits than its factorization.

861857840 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 579 (or 573 counting only the distinct ones).

The product of its (nonzero) digits is 430080, while the sum is 47.

The square root of 861857840 is about 29357.4154175738. The cubic root of 861857840 is about 951.6528345992.

The spelling of 861857840 in words is "eight hundred sixty-one million, eight hundred fifty-seven thousand, eight hundred forty".