91489891 has 4 divisors (see below), whose sum is σ = 91729152. Its totient is φ = 91250632.

The previous prime is 91489873. The next prime is 91489919. The reversal of 91489891 is 19898419.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 19898419 = 4357 ⋅4567.

It is a cyclic number.

It is not a de Polignac number, because 91489891 - 2⁹ = 91489379 is a prime.

It is a Smith number, since the sum of its digits (49) coincides with the sum of the digits of its prime factors. Since it is squarefree, it is also a hoax number.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (91489831) 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, 119056 + ... + 119821.

It is an arithmetic number, because the mean of its divisors is an integer number (22932288).

Almost surely, 2^91489891 is an apocalyptic number.

91489891 is a deficient number, since it is larger than the sum of its proper divisors (239261).

91489891 is a wasteful number, since it uses less digits than its factorization.

91489891 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 239260.

The product of its digits is 186624, while the sum is 49.

The square root of 91489891 is about 9565.0348143642. The cubic root of 91489891 is about 450.5998436829.

The spelling of 91489891 in words is "ninety-one million, four hundred eighty-nine thousand, eight hundred ninety-one".