91891811 has 4 divisors (see below), whose sum is σ = 100245624. Its totient is φ = 83538000.

The previous prime is 91891799. The next prime is 91891829. The reversal of 91891811 is 11819819.

It is a semiprime because it is the product of two primes.

It is a cyclic number.

It is not a de Polignac number, because 91891811 - 2⁶ = 91891747 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (91891841) 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 3 ways as a sum of consecutive naturals, for example, 4176890 + ... + 4176911.

It is an arithmetic number, because the mean of its divisors is an integer number (25061406).

Almost surely, 2^91891811 is an apocalyptic number.

91891811 is a deficient number, since it is larger than the sum of its proper divisors (8353813).

91891811 is a wasteful number, since it uses less digits than its factorization.

91891811 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 8353812.

The product of its digits is 5184, while the sum is 38.

The square root of 91891811 is about 9586.0216461262. The cubic root of 91891811 is about 451.2587162319.

It can be divided in two parts, 918 and 91811, that added together give a palindrome (92729).

The spelling of 91891811 in words is "ninety-one million, eight hundred ninety-one thousand, eight hundred eleven".