21919189 has 2 divisors, whose sum is σ = 21919190. Its totient is φ = 21919188.

The previous prime is 21919181. The next prime is 21919213. The reversal of 21919189 is 98191912.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 20884900 + 1034289 = 4570^2 + 1017^2 .

It is a cyclic number.

It is not a de Polignac number, because 21919189 - 2³ = 21919181 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (21919181) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10959594 + 10959595.

It is an arithmetic number, because the mean of its divisors is an integer number (10959595).

Almost surely, 2^21919189 is an apocalyptic number.

It is an amenable number.

21919189 is a deficient number, since it is larger than the sum of its proper divisors (1).

21919189 is an equidigital number, since it uses as much as digits as its factorization.

21919189 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 11664, while the sum is 40.

The square root of 21919189 is about 4681.7933529792. The cubic root of 21919189 is about 279.8604278878.

It can be divided in two parts, 2 and 1919189, that added together give a palindrome (1919191).

The spelling of 21919189 in words is "twenty-one million, nine hundred nineteen thousand, one hundred eighty-nine".