81864117 has 6 divisors (see below), whose sum is σ = 118248182. Its totient is φ = 54576072.

The previous prime is 81864113. The next prime is 81864161. The reversal of 81864117 is 71146818.

81864117 is a `hidden beast` number, since 8 + 1 + 8 + 641 + 1 + 7 = 666.

It can be written as a sum of positive squares in only one way, i.e., 79816356 + 2047761 = 8934^2 + 1431^2 .

It is not a de Polignac number, because 81864117 - 2² = 81864113 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (81864113) 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 5 ways as a sum of consecutive naturals, for example, 4547998 + ... + 4548015.

Almost surely, 2^81864117 is an apocalyptic number.

It is an amenable number.

81864117 is a deficient number, since it is larger than the sum of its proper divisors (36384065).

81864117 is a wasteful number, since it uses less digits than its factorization.

81864117 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 9096019 (or 9096016 counting only the distinct ones).

The product of its digits is 10752, while the sum is 36.

The square root of 81864117 is about 9047.8791437552. The cubic root of 81864117 is about 434.2080398106.

The spelling of 81864117 in words is "eighty-one million, eight hundred sixty-four thousand, one hundred seventeen".