21939189 has 4 divisors (see below), whose sum is σ = 29252256. Its totient is φ = 14626124.

The previous prime is 21939179. The next prime is 21939233. The reversal of 21939189 is 98193912.

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 not a de Polignac number, because 21939189 - 2¹¹ = 21937141 is a prime.

It is a self number, because there is not a number n which added to its sum of digits gives 21939189.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21939139) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 3656529 + ... + 3656534.

It is an arithmetic number, because the mean of its divisors is an integer number (7313064).

Almost surely, 2^21939189 is an apocalyptic number.

It is an amenable number.

21939189 is a deficient number, since it is larger than the sum of its proper divisors (7313067).

21939189 is an equidigital number, since it uses as much as digits as its factorization.

21939189 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 7313066.

The product of its digits is 34992, while the sum is 42.

The square root of 21939189 is about 4683.9287996296. The cubic root of 21939189 is about 279.9455208634.

The spelling of 21939189 in words is "twenty-one million, nine hundred thirty-nine thousand, one hundred eighty-nine".