81564392 has 64 divisors (see below), whose sum is σ = 189571200. Its totient is φ = 32037120.

The previous prime is 81564389. The next prime is 81564401. The reversal of 81564392 is 29346518.

It is a happy 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 15 ways as a sum of consecutive naturals, for example, 131459 + ... + 132077.

It is an arithmetic number, because the mean of its divisors is an integer number (2962050).

Almost surely, 2^81564392 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 81564392, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (94785600).

81564392 is an abundant number, since it is smaller than the sum of its proper divisors (108006808).

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

81564392 is a wasteful number, since it uses less digits than its factorization.

81564392 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 826 (or 822 counting only the distinct ones).

The product of its digits is 51840, while the sum is 38.

The square root of 81564392 is about 9031.3006815187. The cubic root of 81564392 is about 433.6774770437.

The spelling of 81564392 in words is "eighty-one million, five hundred sixty-four thousand, three hundred ninety-two".