81580805 has 8 divisors (see below), whose sum is σ = 98064000. Its totient is φ = 65153296.

The previous prime is 81580801. The next prime is 81580823. The reversal of 81580805 is 50808518.

It is a sphenic number, since it is the product of 3 distinct primes.

It is a cyclic number.

It is not a de Polignac number, because 81580805 - 2² = 81580801 is a prime.

It is a Curzon number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (81580801) 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 7 ways as a sum of consecutive naturals, for example, 10625 + ... + 16614.

It is an arithmetic number, because the mean of its divisors is an integer number (12258000).

Almost surely, 2^81580805 is an apocalyptic number.

It is an amenable number.

81580805 is a deficient number, since it is larger than the sum of its proper divisors (16483195).

81580805 is a wasteful number, since it uses less digits than its factorization.

81580805 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 27843.

The product of its (nonzero) digits is 12800, while the sum is 35.

The square root of 81580805 is about 9032.2093089122. The cubic root of 81580805 is about 433.7065643732.

The spelling of 81580805 in words is "eighty-one million, five hundred eighty thousand, eight hundred five".