91811819 has 16 divisors (see below), whose sum is σ = 105884160. Its totient is φ = 78732000.

The previous prime is 91811813. The next prime is 91811851.

91811819 is nontrivially palindromic in base 10.

It is a cyclic number.

It is not a de Polignac number, because 91811819 - 2⁸ = 91811563 is a prime.

It is a super-2 number, since 2×91811819² = 16858820216177522, which contains 22 as substring.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (91811813) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (19) of ones.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 55829 + ... + 57449.

It is an arithmetic number, because the mean of its divisors is an integer number (6617760).

Almost surely, 2^91811819 is an apocalyptic number.

91811819 is a deficient number, since it is larger than the sum of its proper divisors (14072341).

91811819 is a wasteful number, since it uses less digits than its factorization.

91811819 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1922.

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

The square root of 91811819 is about 9581.8484124933. The cubic root of 91811819 is about 451.1277376891.

The spelling of 91811819 in words is "ninety-one million, eight hundred eleven thousand, eight hundred nineteen".