91819009091 has 4 divisors (see below), whose sum is σ = 91820121552. Its totient is φ = 91817896632.

The previous prime is 91819009063. The next prime is 91819009123. The reversal of 91819009091 is 19090091819.

It is a happy number.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 19090091819 = 6899 ⋅2767081.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-91819009091 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (91819009001) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 421556 + ... + 601121.

It is an arithmetic number, because the mean of its divisors is an integer number (22955030388).

Almost surely, 2^91819009091 is an apocalyptic number.

91819009091 is a deficient number, since it is larger than the sum of its proper divisors (1112461).

91819009091 is a wasteful number, since it uses less digits than its factorization.

91819009091 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1112460.

The product of its (nonzero) digits is 52488, while the sum is 47.

The spelling of 91819009091 in words is "ninety-one billion, eight hundred nineteen million, nine thousand, ninety-one".