21189023 has 4 divisors (see below), whose sum is σ = 21277920. Its totient is φ = 21100128.

The previous prime is 21189019. The next prime is 21189041. The reversal of 21189023 is 32098112.

It is a semiprime because it is the product of two primes.

It is a cyclic number.

It is not a de Polignac number, because 21189023 - 2² = 21189019 is a prime.

It is a Duffinian number.

It is a junction number, because it is equal to n+sod(n) for n = 21188983 and 21189001.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21189323) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 44090 + ... + 44567.

It is an arithmetic number, because the mean of its divisors is an integer number (5319480).

Almost surely, 2^21189023 is an apocalyptic number.

21189023 is a deficient number, since it is larger than the sum of its proper divisors (88897).

21189023 is an equidigital number, since it uses as much as digits as its factorization.

21189023 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 88896.

The product of its (nonzero) digits is 864, while the sum is 26.

The square root of 21189023 is about 4603.1535929187. The cubic root of 21189023 is about 276.7177243232.

The spelling of 21189023 in words is "twenty-one million, one hundred eighty-nine thousand, twenty-three".