21842189 has 4 divisors (see below), whose sum is σ = 21860256. Its totient is φ = 21824124.

The previous prime is 21842179. The next prime is 21842207. The reversal of 21842189 is 98124812.

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.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-21842189 is a prime.

It is a Duffinian number.

It is a Curzon number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21842179) 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, 7079 + ... + 9684.

It is an arithmetic number, because the mean of its divisors is an integer number (5465064).

Almost surely, 2^21842189 is an apocalyptic number.

It is an amenable number.

21842189 is a deficient number, since it is larger than the sum of its proper divisors (18067).

21842189 is a wasteful number, since it uses less digits than its factorization.

21842189 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 18066.

The product of its digits is 9216, while the sum is 35.

The square root of 21842189 is about 4673.5627737306. The cubic root of 21842189 is about 279.5323358251.

The spelling of 21842189 in words is "twenty-one million, eight hundred forty-two thousand, one hundred eighty-nine".