81665116 has 24 divisors (see below), whose sum is σ = 162009680. Its totient is φ = 35707392.

The previous prime is 81665113. The next prime is 81665117. The reversal of 81665116 is 61156618.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (81665113) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 40341 + ... + 42316.

Almost surely, 2^81665116 is an apocalyptic number.

It is an amenable number.

81665116 is a deficient number, since it is larger than the sum of its proper divisors (80344564).

81665116 is a wasteful number, since it uses less digits than its factorization.

81665116 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 82693 (or 82691 counting only the distinct ones).

The product of its digits is 8640, while the sum is 34.

The square root of 81665116 is about 9036.8753449409. The cubic root of 81665116 is about 433.8559199507.

The spelling of 81665116 in words is "eighty-one million, six hundred sixty-five thousand, one hundred sixteen".