11643611891 has 4 divisors (see below), whose sum is σ = 11669090712. Its totient is φ = 11618133072.

The previous prime is 11643611887. The next prime is 11643611897. The reversal of 11643611891 is 19811634611.

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

It is a cyclic number.

It is not a de Polignac number, because 11643611891 - 2² = 11643611887 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (11643611897) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 12738725 + ... + 12739638.

It is an arithmetic number, because the mean of its divisors is an integer number (2917272678).

Almost surely, 2^11643611891 is an apocalyptic number.

11643611891 is a deficient number, since it is larger than the sum of its proper divisors (25478821).

11643611891 is an equidigital number, since it uses as much as digits as its factorization.

11643611891 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 25478820.

The product of its digits is 31104, while the sum is 41.

The spelling of 11643611891 in words is "eleven billion, six hundred forty-three million, six hundred eleven thousand, eight hundred ninety-one".