11891881 has 4 divisors (see below), whose sum is σ = 11957764. Its totient is φ = 11826000.

The previous prime is 11891833. The next prime is 11891917. The reversal of 11891881 is 18819811.

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 5363856 + 6528025 = 2316^2 + 2555^2 .

It is a cyclic number.

It is not a de Polignac number, because 11891881 - 2¹³ = 11883689 is a prime.

It is a super-2 number, since 2×11891881² = 282833667436322, which contains 22 as substring.

It is a Duffinian number.

It is a self number, because there is not a number n which added to its sum of digits gives 11891881.

It is not an unprimeable number, because it can be changed into a prime (11891801) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 32670 + ... + 33031.

It is an arithmetic number, because the mean of its divisors is an integer number (2989441).

Almost surely, 2^11891881 is an apocalyptic number.

It is an amenable number.

11891881 is a deficient number, since it is larger than the sum of its proper divisors (65883).

11891881 is an equidigital number, since it uses as much as digits as its factorization.

11891881 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 65882.

The product of its digits is 4608, while the sum is 37.

The square root of 11891881 is about 3448.4606710821. The cubic root of 11891881 is about 228.2531877540.

The spelling of 11891881 in words is "eleven million, eight hundred ninety-one thousand, eight hundred eighty-one".