81664612 has 12 divisors (see below), whose sum is σ = 143544240. Its totient is φ = 40651976.

The previous prime is 81664523. The next prime is 81664619. The reversal of 81664612 is 21646618.

It is a super-2 number, since 2×81664612² = 13338217706221088, which contains 22 as substring.

It is not an unprimeable number, because it can be changed into a prime (81664619) 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 3 ways as a sum of consecutive naturals, for example, 44062 + ... + 45877.

It is an arithmetic number, because the mean of its divisors is an integer number (11962020).

Almost surely, 2^81664612 is an apocalyptic number.

It is an amenable number.

81664612 is a deficient number, since it is larger than the sum of its proper divisors (61879628).

81664612 is a wasteful number, since it uses less digits than its factorization.

81664612 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 90170 (or 90168 counting only the distinct ones).

The product of its digits is 13824, while the sum is 34.

The square root of 81664612 is about 9036.8474591530. The cubic root of 81664612 is about 433.8550274283.

The spelling of 81664612 in words is "eighty-one million, six hundred sixty-four thousand, six hundred twelve".