81445989740544 has 1872 divisors, whose sum is σ = 296991275293440. Its totient is φ = 21254897664000.

The previous prime is 81445989740503. The next prime is 81445989740551. The reversal of 81445989740544 is 44504798954418.

81445989740544 is a `hidden beast` number, since 8 + 1 + 4 + 4 + 5 + 9 + 8 + 9 + 74 + 0 + 544 = 666.

It is a tau number, because it is divible by the number of its divisors (1872).

It is a Harshad number since it is a multiple of its sum of digits (72).

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 143 ways as a sum of consecutive naturals, for example, 92447206984 + ... + 92447207864.

It is an arithmetic number, because the mean of its divisors is an integer number (158649185520).

Almost surely, 2^{81445989740544} is an apocalyptic number.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 81445989740544, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (148495637646720).

81445989740544 is an abundant number, since it is smaller than the sum of its proper divisors (215545285552896).

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

81445989740544 is a wasteful number, since it uses less digits than its factorization.

81445989740544 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1038 (or 1000 counting only the distinct ones).

The product of its (nonzero) digits is 928972800, while the sum is 72.

The spelling of 81445989740544 in words is "eighty-one trillion, four hundred forty-five billion, nine hundred eighty-nine million, seven hundred forty thousand, five hundred forty-four".