81080605 has 4 divisors (see below), whose sum is σ = 97296732. Its totient is φ = 64864480.

The previous prime is 81080603. The next prime is 81080611. The reversal of 81080605 is 50608018.

It is a happy number.

It is a semiprime because it is the product of two primes.

It can be written as a sum of positive squares in 2 ways, for example, as 20894041 + 60186564 = 4571^2 + 7758^2 .

It is not a de Polignac number, because 81080605 - 2¹ = 81080603 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (81080603) 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 3 ways as a sum of consecutive naturals, for example, 8108056 + ... + 8108065.

It is an arithmetic number, because the mean of its divisors is an integer number (24324183).

Almost surely, 2^81080605 is an apocalyptic number.

It is an amenable number.

81080605 is a deficient number, since it is larger than the sum of its proper divisors (16216127).

81080605 is a wasteful number, since it uses less digits than its factorization.

81080605 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 16216126.

The product of its (nonzero) digits is 1920, while the sum is 28.

The square root of 81080605 is about 9004.4769420550. The cubic root of 81080605 is about 432.8183451491.

The spelling of 81080605 in words is "eighty-one million, eighty thousand, six hundred five".