21238439 has 4 divisors (see below), whose sum is σ = 21507360. Its totient is φ = 20969520.

The previous prime is 21238433. The next prime is 21238471. The reversal of 21238439 is 93483212.

It is a happy number.

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

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-21238439 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21238433) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 134342 + ... + 134499.

It is an arithmetic number, because the mean of its divisors is an integer number (5376840).

Almost surely, 2^21238439 is an apocalyptic number.

21238439 is a deficient number, since it is larger than the sum of its proper divisors (268921).

21238439 is an equidigital number, since it uses as much as digits as its factorization.

21238439 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 268920.

The product of its digits is 10368, while the sum is 32.

The square root of 21238439 is about 4608.5180915344. The cubic root of 21238439 is about 276.9326731460.

The spelling of 21238439 in words is "twenty-one million, two hundred thirty-eight thousand, four hundred thirty-nine".