21433439 has 2 divisors, whose sum is σ = 21433440. Its totient is φ = 21433438.

The previous prime is 21433427. The next prime is 21433441. The reversal of 21433439 is 93433412.

It is a strong prime.

It is a cyclic number.

It is not a de Polignac number, because 21433439 - 2²⁰ = 20384863 is a prime.

Together with 21433441, it forms a pair of twin primes.

It is a Chen prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (21433469) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10716719 + 10716720.

It is an arithmetic number, because the mean of its divisors is an integer number (10716720).

Almost surely, 2^21433439 is an apocalyptic number.

21433439 is a deficient number, since it is larger than the sum of its proper divisors (1).

21433439 is an equidigital number, since it uses as much as digits as its factorization.

21433439 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 7776, while the sum is 29.

The square root of 21433439 is about 4629.6262268136. The cubic root of 21433439 is about 277.7776416651. Note that the first 3 decimals are identical.

The spelling of 21433439 in words is "twenty-one million, four hundred thirty-three thousand, four hundred thirty-nine".