81609643984 has 40 divisors (see below), whose sum is σ = 173752236288. Its totient is φ = 36824513280.

The previous prime is 81609643949. The next prime is 81609643987. The reversal of 81609643984 is 48934690618.

It is a happy number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (81609643987) 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 7 ways as a sum of consecutive naturals, for example, 1668192 + ... + 1716415.

Almost surely, 2^81609643984 is an apocalyptic number.

It is an amenable number.

81609643984 is an abundant number, since it is smaller than the sum of its proper divisors (92142592304).

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

81609643984 is a wasteful number, since it uses less digits than its factorization.

81609643984 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 3384763 (or 3384757 counting only the distinct ones).

The product of its (nonzero) digits is 8957952, while the sum is 58.

The spelling of 81609643984 in words is "eighty-one billion, six hundred nine million, six hundred forty-three thousand, nine hundred eighty-four".