21911189 has 4 divisors (see below), whose sum is σ = 21922656. Its totient is φ = 21899724.

The previous prime is 21911167. The next prime is 21911213. The reversal of 21911189 is 98111912.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4, and also a brilliant number, because the two primes have the same length.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-21911189 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21911119) 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, 2099 + ... + 6944.

It is an arithmetic number, because the mean of its divisors is an integer number (5480664).

Almost surely, 2^21911189 is an apocalyptic number.

It is an amenable number.

21911189 is a deficient number, since it is larger than the sum of its proper divisors (11467).

21911189 is an equidigital number, since it uses as much as digits as its factorization.

21911189 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 11466.

The product of its digits is 1296, while the sum is 32.

The square root of 21911189 is about 4680.9389015453. The cubic root of 21911189 is about 279.8263762043.

It can be divided in two parts, 2 and 1911189, that added together give a palindrome (1911191).

The spelling of 21911189 in words is "twenty-one million, nine hundred eleven thousand, one hundred eighty-nine".