91915881 has 8 divisors (see below), whose sum is σ = 125866944. Its totient is φ = 59621040.

The previous prime is 91915871. The next prime is 91915909. The reversal of 91915881 is 18851919.

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

It is not a de Polignac number, because 91915881 - 2¹⁹ = 91391593 is a prime.

It is a super-2 number, since 2×91915881² = 16897058360012322, which contains 22 as substring.

It is not an unprimeable number, because it can be changed into a prime (91915801) 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, 413925 + ... + 414146.

It is an arithmetic number, because the mean of its divisors is an integer number (15733368).

Almost surely, 2^91915881 is an apocalyptic number.

It is an amenable number.

91915881 is a deficient number, since it is larger than the sum of its proper divisors (33951063).

91915881 is a wasteful number, since it uses less digits than its factorization.

91915881 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 828111.

The product of its digits is 25920, while the sum is 42.

The square root of 91915881 is about 9587.2770378247. The cubic root of 91915881 is about 451.2981134642.

The spelling of 91915881 in words is "ninety-one million, nine hundred fifteen thousand, eight hundred eighty-one".