81085558 has 4 divisors (see below), whose sum is σ = 121628340. Its totient is φ = 40542778.

The previous prime is 81085549. The next prime is 81085579. The reversal of 81085558 is 85558018.

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

It is a super-3 number, since 3×81085558³ (a number of 25 digits) contains 333 as substring.

It is a Smith number, since the sum of its digits (40) coincides with the sum of the digits of its prime factors. Since it is squarefree, it is also a hoax number.

It is a self number, because there is not a number n which added to its sum of digits gives 81085558.

It is a congruent number.

It is an unprimeable number.

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 as a sum of consecutive naturals, namely, 20271388 + ... + 20271391.

It is an arithmetic number, because the mean of its divisors is an integer number (30407085).

Almost surely, 2^81085558 is an apocalyptic number.

81085558 is a deficient number, since it is larger than the sum of its proper divisors (40542782).

81085558 is a wasteful number, since it uses less digits than its factorization.

81085558 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 40542781.

The product of its (nonzero) digits is 64000, while the sum is 40.

The square root of 81085558 is about 9004.7519677113. The cubic root of 81085558 is about 432.8271582128.

It can be divided in two parts, 810 and 85558, that added together give a palindrome (86368).

The spelling of 81085558 in words is "eighty-one million, eighty-five thousand, five hundred fifty-eight".