81854591 has 16 divisors (see below), whose sum is σ = 100957248. Its totient is φ = 64627200.

The previous prime is 81854537. The next prime is 81854599. The reversal of 81854591 is 19545818.

It is a cyclic number.

It is not a de Polignac number, because 81854591 - 2²² = 77660287 is a prime.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (81854599) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 79661 + ... + 80681.

It is an arithmetic number, because the mean of its divisors is an integer number (6309828).

Almost surely, 2^81854591 is an apocalyptic number.

81854591 is a deficient number, since it is larger than the sum of its proper divisors (19102657).

81854591 is a wasteful number, since it uses less digits than its factorization.

81854591 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1922.

The product of its digits is 57600, while the sum is 41.

The square root of 81854591 is about 9047.3527067314. The cubic root of 81854591 is about 434.1911971597.

The spelling of 81854591 in words is "eighty-one million, eight hundred fifty-four thousand, five hundred ninety-one".