81188064 has 144 divisors (see below), whose sum is σ = 250220880. Its totient is φ = 24883200.

The previous prime is 81188059. The next prime is 81188089. The reversal of 81188064 is 46088118.

It is a tau number, because it is divible by the number of its divisors (144).

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

It is a congruent number.

It is an unprimeable number.

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, 202264 + ... + 202664.

It is an arithmetic number, because the mean of its divisors is an integer number (1737645).

Almost surely, 2^81188064 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 81188064, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (125110440).

81188064 is an abundant number, since it is smaller than the sum of its proper divisors (169032816).

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

81188064 is a wasteful number, since it uses less digits than its factorization.

81188064 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 473 (or 462 counting only the distinct ones).

The product of its (nonzero) digits is 12288, while the sum is 36.

The square root of 81188064 is about 9010.4419425464. The cubic root of 81188064 is about 433.0094705707.

The spelling of 81188064 in words is "eighty-one million, one hundred eighty-eight thousand, sixty-four".