81912085 has 8 divisors (see below), whose sum is σ = 102568320. Its totient is φ = 62680464.

The previous prime is 81912071. The next prime is 81912109. The reversal of 81912085 is 58021918.

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 81912085 - 2⁵ = 81912053 is a prime.

It is a self number, because there is not a number n which added to its sum of digits gives 81912085.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 356025 + ... + 356254.

It is an arithmetic number, because the mean of its divisors is an integer number (12821040).

Almost surely, 2^81912085 is an apocalyptic number.

It is an amenable number.

81912085 is a deficient number, since it is larger than the sum of its proper divisors (20656235).

81912085 is a wasteful number, since it uses less digits than its factorization.

81912085 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 712307.

The product of its (nonzero) digits is 5760, while the sum is 34.

The square root of 81912085 is about 9050.5295425185. The cubic root of 81912085 is about 434.2928308248.

The spelling of 81912085 in words is "eighty-one million, nine hundred twelve thousand, eighty-five".