81660023424 has 256 divisors, whose sum is σ = 284328345600. Its totient is φ = 22578600960.

The previous prime is 81660023381. The next prime is 81660023441. The reversal of 81660023424 is 42432006618.

81660023424 is a `hidden beast` number, since 8 + 1 + 6 + 600 + 2 + 3 + 42 + 4 = 666.

It is a Harshad number since it is a multiple of its sum of digits (36).

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 31 ways as a sum of consecutive naturals, for example, 695509 + ... + 804395.

It is an arithmetic number, because the mean of its divisors is an integer number (1110657600).

Almost surely, 2^81660023424 is an apocalyptic number.

81660023424 is a gapful number since it is divisible by the number (84) formed by its first and last digit.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 81660023424, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (142164172800).

81660023424 is an abundant number, since it is smaller than the sum of its proper divisors (202668322176).

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

81660023424 is a wasteful number, since it uses less digits than its factorization.

81660023424 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 108948 (or 108930 counting only the distinct ones).

The product of its (nonzero) digits is 55296, while the sum is 36.

The spelling of 81660023424 in words is "eighty-one billion, six hundred sixty million, twenty-three thousand, four hundred twenty-four".