81858373 has 4 divisors (see below), whose sum is σ = 82778220. Its totient is φ = 80938528.

The previous prime is 81858367. The next prime is 81858409. The reversal of 81858373 is 37385818.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 37385818 = 2 ⋅18692909.

It can be written as a sum of positive squares in 2 ways, for example, as 30492484 + 51365889 = 5522^2 + 7167^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-81858373 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (81858353) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 459790 + ... + 459967.

It is an arithmetic number, because the mean of its divisors is an integer number (20694555).

Almost surely, 2^81858373 is an apocalyptic number.

It is an amenable number.

81858373 is a deficient number, since it is larger than the sum of its proper divisors (919847).

81858373 is an equidigital number, since it uses as much as digits as its factorization.

81858373 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 919846.

The product of its digits is 161280, while the sum is 43.

The square root of 81858373 is about 9047.5617157331. The cubic root of 81858373 is about 434.1978841632.

The spelling of 81858373 in words is "eighty-one million, eight hundred fifty-eight thousand, three hundred seventy-three".