81817085 has 32 divisors (see below), whose sum is σ = 114780672. Its totient is φ = 54835200.

The previous prime is 81817081. The next prime is 81817093. The reversal of 81817085 is 58071818.

It is not a de Polignac number, because 81817085 - 2² = 81817081 is a prime.

It is a Duffinian number.

It is a Curzon number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (81817081) by changing a digit.

It is a polite number, since it can be written in 31 ways as a sum of consecutive naturals, for example, 541760 + ... + 541910.

It is an arithmetic number, because the mean of its divisors is an integer number (3586896).

Almost surely, 2^81817085 is an apocalyptic number.

It is an amenable number.

81817085 is a deficient number, since it is larger than the sum of its proper divisors (32963587).

81817085 is a wasteful number, since it uses less digits than its factorization.

81817085 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 413.

The product of its (nonzero) digits is 17920, while the sum is 38.

The square root of 81817085 is about 9045.2797082235. The cubic root of 81817085 is about 434.1248711593.

The spelling of 81817085 in words is "eighty-one million, eight hundred seventeen thousand, eighty-five".