13811891 has 4 divisors (see below), whose sum is σ = 14412432. Its totient is φ = 13211352.

The previous prime is 13811857. The next prime is 13811893. The reversal of 13811891 is 19811831.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 19811831 = 13 ⋅1523987.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-13811891 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (13811893) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 300236 + ... + 300281.

It is an arithmetic number, because the mean of its divisors is an integer number (3603108).

Almost surely, 2^13811891 is an apocalyptic number.

13811891 is a deficient number, since it is larger than the sum of its proper divisors (600541).

13811891 is an equidigital number, since it uses as much as digits as its factorization.

13811891 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 600540.

The product of its digits is 1728, while the sum is 32.

The square root of 13811891 is about 3716.4352543802. The cubic root of 13811891 is about 239.9299042980.

The spelling of 13811891 in words is "thirteen million, eight hundred eleven thousand, eight hundred ninety-one".