81575605 has 16 divisors (see below), whose sum is σ = 105354864. Its totient is φ = 60410880.

The previous prime is 81575591. The next prime is 81575617. The reversal of 81575605 is 50657518.

It can be written as a sum of positive squares in 8 ways, for example, as 15673681 + 65901924 = 3959^2 + 8118^2 .

It is not a de Polignac number, because 81575605 - 2⁵ = 81575573 is a prime.

It is a super-2 number, since 2×81575605² = 13309158662232050, which contains 22 as substring.

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, 2682 + ... + 13051.

It is an arithmetic number, because the mean of its divisors is an integer number (6584679).

Almost surely, 2^81575605 is an apocalyptic number.

81575605 is a gapful number since it is divisible by the number (85) formed by its first and last digit.

It is an amenable number.

81575605 is a deficient number, since it is larger than the sum of its proper divisors (23779259).

81575605 is a wasteful number, since it uses less digits than its factorization.

81575605 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 15816.

The product of its (nonzero) digits is 42000, while the sum is 37.

The square root of 81575605 is about 9031.9214456283. The cubic root of 81575605 is about 433.6973492886.

The spelling of 81575605 in words is "eighty-one million, five hundred seventy-five thousand, six hundred five".