861640844 has 18 divisors (see below), whose sum is σ = 1517678820. Its totient is φ = 428023072.

The previous prime is 861640811. The next prime is 861640847. The reversal of 861640844 is 448046168.

861640844 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 (861640847) by changing a digit.

It is a polite number, since it can be written in 5 ways as a sum of consecutive naturals, for example, 784904 + ... + 786000.

It is an arithmetic number, because the mean of its divisors is an integer number (84315490).

Almost surely, 2^861640844 is an apocalyptic number.

It is an amenable number.

861640844 is a deficient number, since it is larger than the sum of its proper divisors (656037976).

861640844 is a wasteful number, since it uses less digits than its factorization.

861640844 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 2377 (or 1278 counting only the distinct ones).

The product of its (nonzero) digits is 147456, while the sum is 41.

The square root of 861640844 is about 29353.7194236097. The cubic root of 861640844 is about 951.5729597899.

The spelling of 861640844 in words is "eight hundred sixty-one million, six hundred forty thousand, eight hundred forty-four".