21443439 has 4 divisors (see below), whose sum is σ = 28591256. Its totient is φ = 14295624.

The previous prime is 21443437. The next prime is 21443447. The reversal of 21443439 is 93434412.

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

It is not a de Polignac number, because 21443439 - 2¹ = 21443437 is a prime.

It is a super-2 number, since 2×21443439² = 919642152293442, which contains 22 as substring.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21443431) 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, 3573904 + ... + 3573909.

It is an arithmetic number, because the mean of its divisors is an integer number (7147814).

Almost surely, 2^21443439 is an apocalyptic number.

21443439 is a deficient number, since it is larger than the sum of its proper divisors (7147817).

21443439 is an equidigital number, since it uses as much as digits as its factorization.

21443439 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 7147816.

The product of its digits is 10368, while the sum is 30.

The square root of 21443439 is about 4630.7061016653. The cubic root of 21443439 is about 277.8208349907.

It can be divided in two parts, 2 and 1443439, that added together give a palindrome (1443441).

The spelling of 21443439 in words is "twenty-one million, four hundred forty-three thousand, four hundred thirty-nine".