21189289 has 4 divisors (see below), whose sum is σ = 23115600. Its totient is φ = 19262980.

The previous prime is 21189283. The next prime is 21189307. The reversal of 21189289 is 98298112.

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 not a de Polignac number, because 21189289 - 2³ = 21189281 is a prime.

It is a Smith number, since the sum of its digits (40) coincides with the sum of the digits of its prime factors. Since it is squarefree, it is also a hoax number.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (21189281) 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, 963139 + ... + 963160.

It is an arithmetic number, because the mean of its divisors is an integer number (5778900).

Almost surely, 2^21189289 is an apocalyptic number.

It is an amenable number.

21189289 is a deficient number, since it is larger than the sum of its proper divisors (1926311).

21189289 is a wasteful number, since it uses less digits than its factorization.

21189289 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1926310.

The product of its digits is 20736, while the sum is 40.

The square root of 21189289 is about 4603.1824860633. The cubic root of 21189289 is about 276.7188822593.

The spelling of 21189289 in words is "twenty-one million, one hundred eighty-nine thousand, two hundred eighty-nine".