861539860 has 12 divisors (see below), whose sum is σ = 1809233748. Its totient is φ = 344615936.

The previous prime is 861539849. The next prime is 861539869. The reversal of 861539860 is 68935168.

It can be written as a sum of positive squares in 2 ways, for example, as 176252176 + 685287684 = 13276^2 + 26178^2 .

It is a self number, because there is not a number n which added to its sum of digits gives 861539860.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (861539869) 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 3 ways as a sum of consecutive naturals, for example, 21538477 + ... + 21538516.

It is an arithmetic number, because the mean of its divisors is an integer number (150769479).

Almost surely, 2^861539860 is an apocalyptic number.

It is an amenable number.

861539860 is an abundant number, since it is smaller than the sum of its proper divisors (947693888).

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

861539860 is a wasteful number, since it uses less digits than its factorization.

861539860 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 43077002 (or 43077000 counting only the distinct ones).

The product of its (nonzero) digits is 311040, while the sum is 46.

The square root of 861539860 is about 29351.9992504770. Note that the first 3 decimals coincide. The cubic root of 861539860 is about 951.5357836668.

The spelling of 861539860 in words is "eight hundred sixty-one million, five hundred thirty-nine thousand, eight hundred sixty".