861895881 has 24 divisors (see below), whose sum is σ = 1552160064. Its totient is φ = 447737760.

The previous prime is 861895877. The next prime is 861895897. The reversal of 861895881 is 188598168.

It is not a de Polignac number, because 861895881 - 2² = 861895877 is a prime.

It is a super-2 number, since 2×861895881² = 1485729019369532322, which contains 22 as substring.

It is a Curzon number.

It is not an unprimeable number, because it can be changed into a prime (861895781) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (19) of ones.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 621166 + ... + 622551.

It is an arithmetic number, because the mean of its divisors is an integer number (64673336).

Almost surely, 2^861895881 is an apocalyptic number.

It is an amenable number.

861895881 is a deficient number, since it is larger than the sum of its proper divisors (690264183).

861895881 is a wasteful number, since it uses less digits than its factorization.

861895881 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1243741 (or 1243738 counting only the distinct ones).

The product of its digits is 1105920, while the sum is 54.

The square root of 861895881 is about 29358.0633046528. The cubic root of 861895881 is about 951.6668358614. Note that the first 3 decimals are identical.

The spelling of 861895881 in words is "eight hundred sixty-one million, eight hundred ninety-five thousand, eight hundred eighty-one".