21333439 has 2 divisors, whose sum is σ = 21333440. Its totient is φ = 21333438.

The previous prime is 21333437. The next prime is 21333451. The reversal of 21333439 is 93433312.

It is a weak prime.

It is a cyclic number.

It is not a de Polignac number, because 21333439 - 2¹ = 21333437 is a prime.

Together with 21333437, it forms a pair of twin primes.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (21333437) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10666719 + 10666720.

It is an arithmetic number, because the mean of its divisors is an integer number (10666720).

Almost surely, 2^21333439 is an apocalyptic number.

21333439 is a deficient number, since it is larger than the sum of its proper divisors (1).

21333439 is an equidigital number, since it uses as much as digits as its factorization.

21333439 is an evil number, because the sum of its binary digits is even.

The product of its digits is 5832, while the sum is 28.

The square root of 21333439 is about 4618.8135922551. The cubic root of 21333439 is about 277.3449676468.

The spelling of 21333439 in words is "twenty-one million, three hundred thirty-three thousand, four hundred thirty-nine".