91906745891 has 4 divisors (see below), whose sum is σ = 91909639632. Its totient is φ = 91903852152.

The previous prime is 91906745867. The next prime is 91906745897. The reversal of 91906745891 is 19854760919.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 19854760919 = 7 ⋅2836394417.

It is a cyclic number.

It is not a de Polignac number, because 91906745891 - 2¹⁴ = 91906729507 is a prime.

It is a Duffinian number.

It is a self number, because there is not a number n which added to its sum of digits gives 91906745891.

It is not an unprimeable number, because it can be changed into a prime (91906745897) 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, 1398695 + ... + 1462928.

It is an arithmetic number, because the mean of its divisors is an integer number (22977409908).

Almost surely, 2^91906745891 is an apocalyptic number.

91906745891 is a deficient number, since it is larger than the sum of its proper divisors (2893741).

91906745891 is a wasteful number, since it uses less digits than its factorization.

91906745891 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 2893740.

The product of its (nonzero) digits is 4898880, while the sum is 59.

The spelling of 91906745891 in words is "ninety-one billion, nine hundred six million, seven hundred forty-five thousand, eight hundred ninety-one".