91881385 has 4 divisors (see below), whose sum is σ = 110257668. Its totient is φ = 73505104.

The previous prime is 91881371. The next prime is 91881401. The reversal of 91881385 is 58318819.

It is a semiprime because it is the product of two primes.

It can be written as a sum of positive squares in 2 ways, for example, as 47844889 + 44036496 = 6917^2 + 6636^2 .

It is a cyclic number.

It is not a de Polignac number, because 91881385 - 2⁵ = 91881353 is a prime.

It is a Duffinian number.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (19) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 9188134 + ... + 9188143.

It is an arithmetic number, because the mean of its divisors is an integer number (27564417).

Almost surely, 2^91881385 is an apocalyptic number.

It is an amenable number.

91881385 is a deficient number, since it is larger than the sum of its proper divisors (18376283).

91881385 is a wasteful number, since it uses less digits than its factorization.

91881385 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 18376282.

The product of its digits is 69120, while the sum is 43.

The square root of 91881385 is about 9585.4778180329. The cubic root of 91881385 is about 451.2416490552.

The spelling of 91881385 in words is "ninety-one million, eight hundred eighty-one thousand, three hundred eighty-five".