81585405 has 48 divisors (see below), whose sum is σ = 157899456. Its totient is φ = 38626560.

The previous prime is 81585403. The next prime is 81585419. The reversal of 81585405 is 50458518.

It is not a de Polignac number, because 81585405 - 2¹ = 81585403 is a prime.

It is a self number, because there is not a number n which added to its sum of digits gives 81585405.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (81585401) by changing a digit.

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 47 ways as a sum of consecutive naturals, for example, 19369 + ... + 23201.

It is an arithmetic number, because the mean of its divisors is an integer number (3289572).

Almost surely, 2^81585405 is an apocalyptic number.

It is an amenable number.

81585405 is a deficient number, since it is larger than the sum of its proper divisors (76314051).

81585405 is a wasteful number, since it uses less digits than its factorization.

81585405 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 3898 (or 3895 counting only the distinct ones).

The product of its (nonzero) digits is 32000, while the sum is 36.

The square root of 81585405 is about 9032.4639495544. The cubic root of 81585405 is about 433.7147158524.

The spelling of 81585405 in words is "eighty-one million, five hundred eighty-five thousand, four hundred five".