91489581 has 10 divisors (see below), whose sum is σ = 136669742. Its totient is φ = 60993000.

The previous prime is 91489571. The next prime is 91489583. The reversal of 91489581 is 18598419.

91489581 is a `hidden beast` number, since 91 + 489 + 5 + 81 = 666.

It can be written as a sum of positive squares in only one way, i.e., 67076100 + 24413481 = 8190^2 + 4941^2 .

It is not a de Polignac number, because 91489581 - 2⁵ = 91489549 is a prime.

It is a super-2 number, since 2×91489581² = 16740686863111122, which contains 22 as substring.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (91489583) by changing a digit.

It is a polite number, since it can be written in 9 ways as a sum of consecutive naturals, for example, 564670 + ... + 564831.

Almost surely, 2^91489581 is an apocalyptic number.

It is an amenable number.

91489581 is a deficient number, since it is larger than the sum of its proper divisors (45180161).

91489581 is a wasteful number, since it uses less digits than its factorization.

91489581 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1129513 (or 1129504 counting only the distinct ones).

The product of its digits is 103680, while the sum is 45.

The square root of 91489581 is about 9565.0186094957. The cubic root of 91489581 is about 450.5993347520.

The spelling of 91489581 in words is "ninety-one million, four hundred eighty-nine thousand, five hundred eighty-one".