81800586 has 96 divisors (see below), whose sum is σ = 218050560. Its totient is φ = 21640608.

The previous prime is 81800557. The next prime is 81800603. The reversal of 81800586 is 68500818.

It is a Curzon number.

It is a self number, because there is not a number n which added to its sum of digits gives 81800586.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 47 ways as a sum of consecutive naturals, for example, 112155 + ... + 112881.

It is an arithmetic number, because the mean of its divisors is an integer number (2271360).

Almost surely, 2^81800586 is an apocalyptic number.

It is a practical number, because each smaller number is the sum of distinct divisors of 81800586, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (109025280).

81800586 is an abundant number, since it is smaller than the sum of its proper divisors (136249974).

It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.

81800586 is a wasteful number, since it uses less digits than its factorization.

81800586 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 808 (or 805 counting only the distinct ones).

The product of its (nonzero) digits is 15360, while the sum is 36.

The square root of 81800586 is about 9044.3676395865. The cubic root of 81800586 is about 434.0956877364.

The spelling of 81800586 in words is "eighty-one million, eight hundred thousand, five hundred eighty-six".