91811938 has 4 divisors (see below), whose sum is σ = 137717910. Its totient is φ = 45905968.

The previous prime is 91811903. The next prime is 91811939. The reversal of 91811938 is 83911819.

It is a happy number.

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., 79512889 + 12299049 = 8917^2 + 3507^2 .

It is a self number, because there is not a number n which added to its sum of digits gives 91811938.

It is not an unprimeable number, because it can be changed into a prime (91811939) 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, 22952983 + ... + 22952986.

Almost surely, 2^91811938 is an apocalyptic number.

91811938 is a deficient number, since it is larger than the sum of its proper divisors (45905972).

91811938 is a wasteful number, since it uses less digits than its factorization.

91811938 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 45905971.

The product of its digits is 15552, while the sum is 40.

The square root of 91811938 is about 9581.8546221491. The cubic root of 91811938 is about 451.1279325957.

The spelling of 91811938 in words is "ninety-one million, eight hundred eleven thousand, nine hundred thirty-eight".