81381186 has 28 divisors (see below), whose sum is σ = 183027222. Its totient is φ = 27126576.

The previous prime is 81381073. The next prime is 81381197. The reversal of 81381186 is 68118318.

It can be written as a sum of positive squares in only one way, i.e., 44475561 + 36905625 = 6669^2 + 6075^2 .

It is a self number, because there is not a number n which added to its sum of digits gives 81381186.

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 13 ways as a sum of consecutive naturals, for example, 26451 + ... + 29366.

Almost surely, 2^81381186 is an apocalyptic number.

81381186 is an abundant number, since it is smaller than the sum of its proper divisors (101646036).

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

81381186 is an equidigital number, since it uses as much as digits as its factorization.

81381186 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 55837 (or 55822 counting only the distinct ones).

The product of its digits is 9216, while the sum is 36.

The square root of 81381186 is about 9021.1521437120. The cubic root of 81381186 is about 433.3525318253.

The spelling of 81381186 in words is "eighty-one million, three hundred eighty-one thousand, one hundred eighty-six".