81681165117 has 12 divisors (see below), whose sum is σ = 118001336544. Its totient is φ = 54446064840.

The previous prime is 81681165113. The next prime is 81681165119. The reversal of 81681165117 is 71156118618.

81681165117 is a `hidden beast` number, since 8 + 16 + 8 + 116 + 511 + 7 = 666.

It is not a de Polignac number, because 81681165117 - 2² = 81681165113 is a prime.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (81681165113) by changing a digit.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 605809 + ... + 728262.

It is an arithmetic number, because the mean of its divisors is an integer number (9833444712).

Almost surely, 2^81681165117 is an apocalyptic number.

It is an amenable number.

81681165117 is a deficient number, since it is larger than the sum of its proper divisors (36320171427).

81681165117 is a wasteful number, since it uses less digits than its factorization.

81681165117 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1340880 (or 1340877 counting only the distinct ones).

The product of its digits is 80640, while the sum is 45.

The spelling of 81681165117 in words is "eighty-one billion, six hundred eighty-one million, one hundred sixty-five thousand, one hundred seventeen".