91866581 has 8 divisors (see below), whose sum is σ = 93644160. Its totient is φ = 90101088.

The previous prime is 91866569. The next prime is 91866587. The reversal of 91866581 is 18566819.

It is a sphenic number, since it is the product of 3 distinct primes.

It is not a de Polignac number, because 91866581 - 2¹⁸ = 91604437 is a prime.

It is a super-2 number, since 2×91866581² = 16878937409259122, 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 (91866587) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 13145 + ... + 18881.

It is an arithmetic number, because the mean of its divisors is an integer number (11705520).

Almost surely, 2^91866581 is an apocalyptic number.

It is an amenable number.

91866581 is a deficient number, since it is larger than the sum of its proper divisors (1777579).

91866581 is a wasteful number, since it uses less digits than its factorization.

91866581 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 6043.

The product of its digits is 103680, while the sum is 44.

The square root of 91866581 is about 9584.7055771161. The cubic root of 91866581 is about 451.2174129521.

The spelling of 91866581 in words is "ninety-one million, eight hundred sixty-six thousand, five hundred eighty-one".