81664512193 has 16 divisors (see below), whose sum is σ = 91992637440. Its totient is φ = 71821976400.

The previous prime is 81664512191. The next prime is 81664512247. The reversal of 81664512193 is 39121546618.

It is a cyclic number.

It is not a de Polignac number, because 81664512193 - 2¹ = 81664512191 is a prime.

It is not an unprimeable number, because it can be changed into a prime (81664512191) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 1042138 + ... + 1117756.

It is an arithmetic number, because the mean of its divisors is an integer number (5749539840).

Almost surely, 2^81664512193 is an apocalyptic number.

It is an amenable number.

81664512193 is a deficient number, since it is larger than the sum of its proper divisors (10328125247).

81664512193 is a wasteful number, since it uses less digits than its factorization.

81664512193 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 78828.

The product of its digits is 311040, while the sum is 46.

The spelling of 81664512193 in words is "eighty-one billion, six hundred sixty-four million, five hundred twelve thousand, one hundred ninety-three".