81664068 has 12 divisors (see below), whose sum is σ = 190549520. Its totient is φ = 27221352.

The previous prime is 81664067. The next prime is 81664111. The reversal of 81664068 is 86046618.

It is a tau number, because it is divible by the number of its divisors (12).

It is a hoax number, since the sum of its digits (39) coincides with the sum of the digits of its distinct prime factors.

It is not an unprimeable number, because it can be changed into a prime (81664061) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 3402658 + ... + 3402681.

Almost surely, 2^81664068 is an apocalyptic number.

It is an amenable number.

81664068 is an abundant number, since it is smaller than the sum of its proper divisors (108885452).

It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.

81664068 is a wasteful number, since it uses less digits than its factorization.

81664068 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 6805346 (or 6805344 counting only the distinct ones).

The product of its (nonzero) digits is 55296, while the sum is 39.

The square root of 81664068 is about 9036.8173601108. The cubic root of 81664068 is about 433.8540640667.

The spelling of 81664068 in words is "eighty-one million, six hundred sixty-four thousand, sixty-eight".