21439239 has 8 divisors (see below), whose sum is σ = 30090240. Its totient is φ = 13540536.

The previous prime is 21439237. The next prime is 21439273. The reversal of 21439239 is 93293412.

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

It is not a de Polignac number, because 21439239 - 2¹ = 21439237 is a prime.

It is a plaindrome in base 11.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21439237) 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, 188007 + ... + 188120.

It is an arithmetic number, because the mean of its divisors is an integer number (3761280).

Almost surely, 2^21439239 is an apocalyptic number.

21439239 is a deficient number, since it is larger than the sum of its proper divisors (8651001).

21439239 is a wasteful number, since it uses less digits than its factorization.

21439239 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 376149.

The product of its digits is 11664, while the sum is 33.

The square root of 21439239 is about 4630.2525849029. The cubic root of 21439239 is about 277.8026954299.

The spelling of 21439239 in words is "twenty-one million, four hundred thirty-nine thousand, two hundred thirty-nine".