81181139 has 8 divisors (see below), whose sum is σ = 87872400. Its totient is φ = 74553696.

The previous prime is 81181117. The next prime is 81181141. The reversal of 81181139 is 93118118.

It is a sphenic number, since it is the product of 3 distinct primes.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-81181139 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (81181159) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 13289 + ... + 18410.

It is an arithmetic number, because the mean of its divisors is an integer number (10984050).

Almost surely, 2^81181139 is an apocalyptic number.

81181139 is a deficient number, since it is larger than the sum of its proper divisors (6691261).

81181139 is a wasteful number, since it uses less digits than its factorization.

81181139 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 31909.

The product of its digits is 1728, while the sum is 32.

The square root of 81181139 is about 9010.0576579731. The cubic root of 81181139 is about 432.9971589258.

The spelling of 81181139 in words is "eighty-one million, one hundred eighty-one thousand, one hundred thirty-nine".