864642861 has 24 divisors (see below), whose sum is σ = 1321320000. Its totient is φ = 543324672.

The previous prime is 864642851. The next prime is 864642869. The reversal of 864642861 is 168246468.

It is not a de Polignac number, because 864642861 - 2⁵ = 864642829 is a prime.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (864642869) by changing a digit.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 21325 + ... + 46733.

It is an arithmetic number, because the mean of its divisors is an integer number (55055000).

Almost surely, 2^864642861 is an apocalyptic number.

It is an amenable number.

864642861 is a deficient number, since it is larger than the sum of its proper divisors (456677139).

864642861 is a wasteful number, since it uses less digits than its factorization.

864642861 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 25633 (or 25630 counting only the distinct ones).

The product of its digits is 442368, while the sum is 45.

The square root of 864642861 is about 29404.8101677260. The cubic root of 864642861 is about 952.6767944300.

The spelling of 864642861 in words is "eight hundred sixty-four million, six hundred forty-two thousand, eight hundred sixty-one".