81640572959 has 24 divisors (see below), whose sum is σ = 97717494000. Its totient is φ = 67887832320.

The previous prime is 81640572919. The next prime is 81640572971. The reversal of 81640572959 is 95927504618.

It is not a de Polignac number, because 81640572959 - 2¹⁶ = 81640507423 is a prime.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (81640572919) 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 23 ways as a sum of consecutive naturals, for example, 545594 + ... + 678935.

It is an arithmetic number, because the mean of its divisors is an integer number (4071562250).

Almost surely, 2^81640572959 is an apocalyptic number.

81640572959 is a deficient number, since it is larger than the sum of its proper divisors (16076921041).

81640572959 is a wasteful number, since it uses less digits than its factorization.

81640572959 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1224599 (or 1224588 counting only the distinct ones).

The product of its (nonzero) digits is 5443200, while the sum is 56.

The spelling of 81640572959 in words is "eighty-one billion, six hundred forty million, five hundred seventy-two thousand, nine hundred fifty-nine".