91208920091 has 4 divisors (see below), whose sum is σ = 91211724384. Its totient is φ = 91206115800.

The previous prime is 91208920073. The next prime is 91208920163. The reversal of 91208920091 is 19002980219.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 19002980219 = 101 ⋅188148319.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-91208920091 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (91208920001) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 1352780 + ... + 1418601.

It is an arithmetic number, because the mean of its divisors is an integer number (22802931096).

Almost surely, 2^91208920091 is an apocalyptic number.

91208920091 is a deficient number, since it is larger than the sum of its proper divisors (2804293).

91208920091 is a wasteful number, since it uses less digits than its factorization.

91208920091 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 2804292.

The product of its (nonzero) digits is 23328, while the sum is 41.

The spelling of 91208920091 in words is "ninety-one billion, two hundred eight million, nine hundred twenty thousand, ninety-one".