81582005 has 16 divisors (see below), whose sum is σ = 100929024. Its totient is φ = 63265920.

The previous prime is 81581917. The next prime is 81582023. The reversal of 81582005 is 50028518.

It is not a de Polignac number, because 81582005 - 2⁸ = 81581749 is a prime.

It is a Duffinian number.

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 15 ways as a sum of consecutive naturals, for example, 33044 + ... + 35426.

It is an arithmetic number, because the mean of its divisors is an integer number (6308064).

Almost surely, 2^81582005 is an apocalyptic number.

It is an amenable number.

81582005 is a deficient number, since it is larger than the sum of its proper divisors (19347019).

81582005 is a wasteful number, since it uses less digits than its factorization.

81582005 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 2596.

The product of its (nonzero) digits is 3200, while the sum is 29.

The square root of 81582005 is about 9032.2757375979. The cubic root of 81582005 is about 433.7086908756.

The spelling of 81582005 in words is "eighty-one million, five hundred eighty-two thousand, five".