21189165 has 16 divisors (see below), whose sum is σ = 34254528. Its totient is φ = 11183616.

The previous prime is 21189163. The next prime is 21189173. The reversal of 21189165 is 56198112.

It is not a de Polignac number, because 21189165 - 2¹ = 21189163 is a prime.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21189163) 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 15 ways as a sum of consecutive naturals, for example, 5827 + ... + 8736.

It is an arithmetic number, because the mean of its divisors is an integer number (2140908).

Almost surely, 2^21189165 is an apocalyptic number.

It is an amenable number.

21189165 is a deficient number, since it is larger than the sum of its proper divisors (13065363).

21189165 is a wasteful number, since it uses less digits than its factorization.

21189165 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 14668.

The product of its digits is 4320, while the sum is 33.

The square root of 21189165 is about 4603.1690171012. The cubic root of 21189165 is about 276.7183424707.

The spelling of 21189165 in words is "twenty-one million, one hundred eighty-nine thousand, one hundred sixty-five".