11665881 has 6 divisors (see below), whose sum is σ = 16850730. Its totient is φ = 7777248.

The previous prime is 11665879. The next prime is 11665903. The reversal of 11665881 is 18856611.

11665881 is a `hidden beast` number, since 11 + 66 + 588 + 1 = 666.

It can be written as a sum of positive squares in only one way, i.e., 10017225 + 1648656 = 3165^2 + 1284^2 .

It is not a de Polignac number, because 11665881 - 2¹ = 11665879 is a prime.

It is a super-2 number, since 2×11665881² = 272185559012322, which contains 22 as substring.

It is not an unprimeable number, because it can be changed into a prime (11665831) by changing a digit.

It is a polite number, since it can be written in 5 ways as a sum of consecutive naturals, for example, 648096 + ... + 648113.

It is an arithmetic number, because the mean of its divisors is an integer number (2808455).

Almost surely, 2^11665881 is an apocalyptic number.

It is an amenable number.

11665881 is a deficient number, since it is larger than the sum of its proper divisors (5184849).

11665881 is a wasteful number, since it uses less digits than its factorization.

11665881 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1296215 (or 1296212 counting only the distinct ones).

The product of its digits is 11520, while the sum is 36.

The square root of 11665881 is about 3415.5352435599. The cubic root of 11665881 is about 226.7979792286.

The spelling of 11665881 in words is "eleven million, six hundred sixty-five thousand, eight hundred eighty-one".