81664533264 has 20 divisors (see below), whose sum is σ = 210966711056. Its totient is φ = 27221511072.

The previous prime is 81664533257. The next prime is 81664533331. The reversal of 81664533264 is 46233546618.

It is a Harshad number since it is a multiple of its sum of digits (48), and also a Moran number because the ratio is a prime number: 1701344443 = 81664533264 / (8 + 1 + 6 + 6 + 4 + 5 + 3 + 3 + 2 + 6 + 4).

It is an unprimeable number.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 850672174 + ... + 850672269.

Almost surely, 2^81664533264 is an apocalyptic number.

It is an amenable number.

81664533264 is an abundant number, since it is smaller than the sum of its proper divisors (129302177792).

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

81664533264 is a wasteful number, since it uses less digits than its factorization.

81664533264 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1701344454 (or 1701344448 counting only the distinct ones).

The product of its digits is 2488320, while the sum is 48.

The spelling of 81664533264 in words is "eighty-one billion, six hundred sixty-four million, five hundred thirty-three thousand, two hundred sixty-four".