861841920 has 160 divisors (see below), whose sum is σ = 2771822592. Its totient is φ = 228442112.

The previous prime is 861841873. The next prime is 861841921. The reversal of 861841920 is 29148168.

It is a tau number, because it is divible by the number of its divisors (160).

It is not an unprimeable number, because it can be changed into a prime (861841921) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 2250049 + ... + 2250431.

Almost surely, 2^861841920 is an apocalyptic number.

861841920 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 861841920, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (1385911296).

861841920 is an abundant number, since it is smaller than the sum of its proper divisors (1909980672).

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

861841920 is a wasteful number, since it uses less digits than its factorization.

861841920 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 702 (or 686 counting only the distinct ones).

The product of its (nonzero) digits is 27648, while the sum is 39.

The square root of 861841920 is about 29357.1442752867. The cubic root of 861841920 is about 951.6469750070.

The spelling of 861841920 in words is "eight hundred sixty-one million, eight hundred forty-one thousand, nine hundred twenty".