81238113 has 24 divisors (see below), whose sum is σ = 131545440. Its totient is φ = 49141080.

The previous prime is 81238111. The next prime is 81238117. The reversal of 81238113 is 31183218.

It is not a de Polignac number, because 81238113 - 2¹ = 81238111 is a prime.

It is a Harshad number since it is a multiple of its sum of digits (27).

It is not an unprimeable number, because it can be changed into a prime (81238111) 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 23 ways as a sum of consecutive naturals, for example, 155070 + ... + 155592.

It is an arithmetic number, because the mean of its divisors is an integer number (5481060).

Almost surely, 2^81238113 is an apocalyptic number.

It is an amenable number.

81238113 is a deficient number, since it is larger than the sum of its proper divisors (50307327).

81238113 is an equidigital number, since it uses as much as digits as its factorization.

81238113 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1066 (or 537 counting only the distinct ones).

The product of its digits is 1152, while the sum is 27.

The square root of 81238113 is about 9013.2187924182. The cubic root of 81238113 is about 433.0984296213.

The spelling of 81238113 in words is "eighty-one million, two hundred thirty-eight thousand, one hundred thirteen".