861819840 has 504 divisors, whose sum is σ = 3577571712. Its totient is φ = 189665280.

The previous prime is 861819781. The next prime is 861819853. The reversal of 861819840 is 48918168.

861819840 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

It is a tau number, because it is divible by the number of its divisors (504).

It is a Harshad number since it is a multiple of its sum of digits (45).

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 71 ways as a sum of consecutive naturals, for example, 4374622 + ... + 4374818.

Almost surely, 2^861819840 is an apocalyptic number.

861819840 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 861819840, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (1788785856).

861819840 is an abundant number, since it is smaller than the sum of its proper divisors (2715751872).

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

861819840 is a wasteful number, since it uses less digits than its factorization.

861819840 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 265 (or 245 counting only the distinct ones).

The product of its (nonzero) digits is 110592, while the sum is 45.

The square root of 861819840 is about 29356.7682145021. The cubic root of 861819840 is about 951.6388480160.

The spelling of 861819840 in words is "eight hundred sixty-one million, eight hundred nineteen thousand, eight hundred forty".