81906318 has 48 divisors (see below), whose sum is σ = 191763936. Its totient is φ = 25116480.

The previous prime is 81906299. The next prime is 81906329. The reversal of 81906318 is 81360918.

81906318 is a `hidden beast` number, since 8 + 19 + 0 + 631 + 8 = 666.

It is a hoax number, since the sum of its digits (36) coincides with the sum of the digits of its distinct prime factors.

It is a congruent number.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 126271 + ... + 126917.

It is an arithmetic number, because the mean of its divisors is an integer number (3995082).

Almost surely, 2^81906318 is an apocalyptic number.

It is a practical number, because each smaller number is the sum of distinct divisors of 81906318, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (95881968).

81906318 is an abundant number, since it is smaller than the sum of its proper divisors (109857618).

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

81906318 is a wasteful number, since it uses less digits than its factorization.

81906318 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1209 (or 1206 counting only the distinct ones).

The product of its (nonzero) digits is 10368, while the sum is 36.

The square root of 81906318 is about 9050.2109367683. The cubic root of 81906318 is about 434.2826384927.

The spelling of 81906318 in words is "eighty-one million, nine hundred six thousand, three hundred eighteen".