91581289 has 4 divisors (see below), whose sum is σ = 92525524. Its totient is φ = 90637056.

The previous prime is 91581263. The next prime is 91581307. The reversal of 91581289 is 98218519.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 98218519 = 7 ⋅14031217.

It can be written as a sum of positive squares in 2 ways, for example, as 73874025 + 17707264 = 8595^2 + 4208^2 .

It is a cyclic number.

It is not a de Polignac number, because 91581289 - 2⁵ = 91581257 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (91581209) 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, 471972 + ... + 472165.

It is an arithmetic number, because the mean of its divisors is an integer number (23131381).

Almost surely, 2^91581289 is an apocalyptic number.

It is an amenable number.

91581289 is a deficient number, since it is larger than the sum of its proper divisors (944235).

91581289 is an equidigital number, since it uses as much as digits as its factorization.

91581289 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 944234.

The product of its digits is 51840, while the sum is 43.

The square root of 91581289 is about 9569.8113356534. The cubic root of 91581289 is about 450.7498428339.

The spelling of 91581289 in words is "ninety-one million, five hundred eighty-one thousand, two hundred eighty-nine".