81139113 has 48 divisors (see below), whose sum is σ = 139142016. Its totient is φ = 44997120.

The previous prime is 81139111. The next prime is 81139133. The reversal of 81139113 is 31193118.

It is a happy number.

It is not a de Polignac number, because 81139113 - 2¹ = 81139111 is a prime.

It is a Curzon number.

It is not an unprimeable number, because it can be changed into a prime (81139111) 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 in 47 ways as a sum of consecutive naturals, for example, 61620 + ... + 62922.

It is an arithmetic number, because the mean of its divisors is an integer number (2898792).

Almost surely, 2^81139113 is an apocalyptic number.

It is an amenable number.

81139113 is a deficient number, since it is larger than the sum of its proper divisors (58002903).

81139113 is a wasteful number, since it uses less digits than its factorization.

81139113 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1374 (or 1371 counting only the distinct ones).

The product of its digits is 648, while the sum is 27.

The square root of 81139113 is about 9007.7251845291. The cubic root of 81139113 is about 432.9224277759.

The spelling of 81139113 in words is "eighty-one million, one hundred thirty-nine thousand, one hundred thirteen".