91781881 has 8 divisors (see below), whose sum is σ = 93529728. Its totient is φ = 90042000.

The previous prime is 91781869. The next prime is 91781887. The reversal of 91781881 is 18818719.

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

It is a cyclic number.

It is not a de Polignac number, because 91781881 - 2¹¹ = 91779833 is a prime.

It is a super-2 number, since 2×91781881² = 16847827359796322, which contains 22 as substring.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (91781887) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 24546 + ... + 28036.

It is an arithmetic number, because the mean of its divisors is an integer number (11691216).

Almost surely, 2^91781881 is an apocalyptic number.

It is an amenable number.

91781881 is a deficient number, since it is larger than the sum of its proper divisors (1747847).

91781881 is a wasteful number, since it uses less digits than its factorization.

91781881 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 3983.

The product of its digits is 32256, while the sum is 43.

The square root of 91781881 is about 9580.2860604473. The cubic root of 91781881 is about 451.0786977775.

The spelling of 91781881 in words is "ninety-one million, seven hundred eighty-one thousand, eight hundred eighty-one".