81385569 has 24 divisors (see below), whose sum is σ = 129130560. Its totient is φ = 49164192.

The previous prime is 81385561. The next prime is 81385573. The reversal of 81385569 is 96558318.

81385569 is a `hidden beast` number, since 8 + 1 + 3 + 85 + 569 = 666.

It is not a de Polignac number, because 81385569 - 2³ = 81385561 is a prime.

It is a super-2 number, since 2×81385569² = 13247221682907522, which contains 22 as substring.

It is not an unprimeable number, because it can be changed into a prime (81385561) 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 23 ways as a sum of consecutive naturals, for example, 6414 + ... + 14279.

It is an arithmetic number, because the mean of its divisors is an integer number (5380440).

Almost surely, 2^81385569 is an apocalyptic number.

It is an amenable number.

81385569 is a deficient number, since it is larger than the sum of its proper divisors (47744991).

81385569 is a wasteful number, since it uses less digits than its factorization.

81385569 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 20741 (or 20738 counting only the distinct ones).

The product of its digits is 259200, while the sum is 45.

The square root of 81385569 is about 9021.3950695001. The cubic root of 81385569 is about 433.3603114696.

The spelling of 81385569 in words is "eighty-one million, three hundred eighty-five thousand, five hundred sixty-nine".