81000085 has 4 divisors (see below), whose sum is σ = 97200108. Its totient is φ = 64800064.

The previous prime is 81000083. The next prime is 81000107. The reversal of 81000085 is 58000018.

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 24344356 + 56655729 = 4934^2 + 7527^2 .

It is a cyclic number.

It is not a de Polignac number, because 81000085 - 2¹ = 81000083 is a prime.

It is a super-2 number, since 2×81000085² = 13122027540014450, which contains 22 as substring.

It is a Smith number, since the sum of its digits (22) coincides with the sum of the digits of its prime factors. Since it is squarefree, it is also a hoax number.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (81000083) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 8100004 + ... + 8100013.

It is an arithmetic number, because the mean of its divisors is an integer number (24300027).

Almost surely, 2^81000085 is an apocalyptic number.

It is an amenable number.

81000085 is a deficient number, since it is larger than the sum of its proper divisors (16200023).

81000085 is a wasteful number, since it uses less digits than its factorization.

81000085 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 16200022.

The product of its (nonzero) digits is 320, while the sum is 22.

The square root of 81000085 is about 9000.0047222210. The cubic root of 81000085 is about 432.6750224393.

The spelling of 81000085 in words is "eighty-one million, eighty-five", and thus it is an aban number and an uban number.