21389523 has 8 divisors (see below), whose sum is σ = 28701648. Its totient is φ = 14168544.

The previous prime is 21389521. The next prime is 21389561. The reversal of 21389523 is 32598312.

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

It is not a de Polignac number, because 21389523 - 2¹ = 21389521 is a prime.

It is a Smith number, since the sum of its digits (33) coincides with the sum of the digits of its prime factors. Since it is squarefree, it is also a hoax number.

It is not an unprimeable number, because it can be changed into a prime (21389521) 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 7 ways as a sum of consecutive naturals, for example, 22236 + ... + 23177.

It is an arithmetic number, because the mean of its divisors is an integer number (3587706).

Almost surely, 2^21389523 is an apocalyptic number.

21389523 is a deficient number, since it is larger than the sum of its proper divisors (7312125).

21389523 is a wasteful number, since it uses less digits than its factorization.

21389523 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 45573.

The product of its digits is 12960, while the sum is 33.

The square root of 21389523 is about 4624.8808633304. The cubic root of 21389523 is about 277.5877946379.

It can be divided in two parts, 21389 and 523, that added together give a palindrome (21912).

The spelling of 21389523 in words is "twenty-one million, three hundred eighty-nine thousand, five hundred twenty-three".