81558005 has 16 divisors (see below), whose sum is σ = 102265200. Its totient is φ = 62361600.

The previous prime is 81557999. The next prime is 81558011. The reversal of 81558005 is 50085518.

It is an interprime number because it is at equal distance from previous prime (81557999) and next prime (81558011).

It can be written as a sum of positive squares in 8 ways, for example, as 305809 + 81252196 = 553^2 + 9014^2 .

It is not a de Polignac number, because 81558005 - 2¹⁶ = 81492469 is a prime.

It is a Curzon 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, 11861 + ... + 17429.

It is an arithmetic number, because the mean of its divisors is an integer number (6391575).

Almost surely, 2^81558005 is an apocalyptic number.

It is an amenable number.

81558005 is a deficient number, since it is larger than the sum of its proper divisors (20707195).

81558005 is a wasteful number, since it uses less digits than its factorization.

81558005 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 5704.

The product of its (nonzero) digits is 8000, while the sum is 32.

The square root of 81558005 is about 9030.9470710441. The cubic root of 81558005 is about 433.6661568655. Note that the first 3 decimals are identical.

The spelling of 81558005 in words is "eighty-one million, five hundred fifty-eight thousand, five".