21189623 has 8 divisors (see below), whose sum is σ = 26079648. Its totient is φ = 16765344.

The previous prime is 21189607. The next prime is 21189629. The reversal of 21189623 is 32698112.

It is a sphenic number, since it is the product of 3 distinct primes.

It is a cyclic number.

It is not a de Polignac number, because 21189623 - 2⁴ = 21189607 is a prime.

It is a self number, because there is not a number n which added to its sum of digits gives 21189623.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21189629) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 116336 + ... + 116517.

It is an arithmetic number, because the mean of its divisors is an integer number (3259956).

Almost surely, 2^21189623 is an apocalyptic number.

21189623 is a deficient number, since it is larger than the sum of its proper divisors (4890025).

21189623 is a wasteful number, since it uses less digits than its factorization.

21189623 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 232873.

The product of its digits is 5184, while the sum is 32.

The square root of 21189623 is about 4603.2187651686. The cubic root of 21189623 is about 276.7203361955.

It can be divided in two parts, 21189 and 623, that added together give a palindrome (21812).

The spelling of 21189623 in words is "twenty-one million, one hundred eighty-nine thousand, six hundred twenty-three".