861718561 has 12 divisors (see below), whose sum is σ = 948656016. Its totient is φ = 782158520.

The previous prime is 861718549. The next prime is 861718577. The reversal of 861718561 is 165817168.

It is not a de Polignac number, because 861718561 - 2¹⁵ = 861685793 is a prime.

It is not an unprimeable number, because it can be changed into a prime (861718591) 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 11 ways as a sum of consecutive naturals, for example, 77430 + ... + 87856.

It is an arithmetic number, because the mean of its divisors is an integer number (79054668).

Almost surely, 2^861718561 is an apocalyptic number.

It is an amenable number.

861718561 is a deficient number, since it is larger than the sum of its proper divisors (86937455).

861718561 is a wasteful number, since it uses less digits than its factorization.

861718561 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 11132 (or 11121 counting only the distinct ones).

The product of its digits is 80640, while the sum is 43.

The square root of 861718561 is about 29355.0431953353. The cubic root of 861718561 is about 951.6015684508.

The spelling of 861718561 in words is "eight hundred sixty-one million, seven hundred eighteen thousand, five hundred sixty-one".