81321858 has 48 divisors (see below), whose sum is σ = 186563520. Its totient is φ = 25556832.

The previous prime is 81321847. The next prime is 81321871. The reversal of 81321858 is 85812318.

It is a super-2 number, since 2×81321858² = 13226489177144328, which contains 22 as substring.

It is a Curzon number.

It is an unprimeable number.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 20635 + ... + 24257.

It is an arithmetic number, because the mean of its divisors is an integer number (3886740).

Almost surely, 2^81321858 is an apocalyptic number.

It is a practical number, because each smaller number is the sum of distinct divisors of 81321858, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (93281760).

81321858 is an abundant number, since it is smaller than the sum of its proper divisors (105241662).

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

81321858 is a wasteful number, since it uses less digits than its factorization.

81321858 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 3703 (or 3700 counting only the distinct ones).

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

The square root of 81321858 is about 9017.8632724166. The cubic root of 81321858 is about 433.2471995799.

The spelling of 81321858 in words is "eighty-one million, three hundred twenty-one thousand, eight hundred fifty-eight".