81664512655 has 64 divisors (see below), whose sum is σ = 117989498880. Its totient is φ = 53561692800.

The previous prime is 81664512649. The next prime is 81664512679. The reversal of 81664512655 is 55621546618.

It is not a de Polignac number, because 81664512655 - 2³ = 81664512647 is a prime.

It is a junction number, because it is equal to n+sod(n) for n = 81664512599 and 81664512608.

It is a congruent number.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written in 63 ways as a sum of consecutive naturals, for example, 5063334 + ... + 5079436.

It is an arithmetic number, because the mean of its divisors is an integer number (1843585920).

Almost surely, 2^81664512655 is an apocalyptic number.

81664512655 is a deficient number, since it is larger than the sum of its proper divisors (36324986225).

81664512655 is a wasteful number, since it uses less digits than its factorization.

81664512655 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 16372.

The product of its digits is 1728000, while the sum is 49.

The spelling of 81664512655 in words is "eighty-one billion, six hundred sixty-four million, five hundred twelve thousand, six hundred fifty-five".