81186338 has 4 divisors (see below), whose sum is σ = 121779510. Its totient is φ = 40593168.

The previous prime is 81186331. The next prime is 81186383. The reversal of 81186338 is 83368118.

It is a semiprime because it is the product of two primes.

It can be written as a sum of positive squares in only one way, i.e., 48958009 + 32228329 = 6997^2 + 5677^2 .

It is a Curzon number.

It is not an unprimeable number, because it can be changed into a prime (81186331) by changing a digit.

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 as a sum of consecutive naturals, namely, 20296583 + ... + 20296586.

Almost surely, 2^81186338 is an apocalyptic number.

81186338 is a deficient number, since it is larger than the sum of its proper divisors (40593172).

81186338 is a wasteful number, since it uses less digits than its factorization.

81186338 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 40593171.

The product of its digits is 27648, while the sum is 38.

The square root of 81186338 is about 9010.3461642714. The cubic root of 81186338 is about 433.0064020587.

The spelling of 81186338 in words is "eighty-one million, one hundred eighty-six thousand, three hundred thirty-eight".