91081138 has 16 divisors (see below), whose sum is σ = 148024800. Its totient is φ = 41864256.

The previous prime is 91081099. The next prime is 91081147. The reversal of 91081138 is 83118019.

It is an unprimeable number.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 29688 + ... + 32611.

It is an arithmetic number, because the mean of its divisors is an integer number (9251550).

Almost surely, 2^91081138 is an apocalyptic number.

91081138 is a deficient number, since it is larger than the sum of its proper divisors (56943662).

91081138 is a wasteful number, since it uses less digits than its factorization.

91081138 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 62361.

The product of its (nonzero) digits is 1728, while the sum is 31.

The square root of 91081138 is about 9543.6438533717. The cubic root of 91081138 is about 449.9277875895.

It can be divided in two parts, 91081 and 138, that added together give a palindrome (91219).

The spelling of 91081138 in words is "ninety-one million, eighty-one thousand, one hundred thirty-eight".