21442439 has 2 divisors, whose sum is σ = 21442440. Its totient is φ = 21442438.

The previous prime is 21442427. The next prime is 21442451. The reversal of 21442439 is 93424412.

It is a balanced prime because it is at equal distance from previous prime (21442427) and next prime (21442451).

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-21442439 is a prime.

It is a Chen prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (21442459) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10721219 + 10721220.

It is an arithmetic number, because the mean of its divisors is an integer number (10721220).

Almost surely, 2^21442439 is an apocalyptic number.

21442439 is a deficient number, since it is larger than the sum of its proper divisors (1).

21442439 is an equidigital number, since it uses as much as digits as its factorization.

21442439 is an evil number, because the sum of its binary digits is even.

The product of its digits is 6912, while the sum is 29.

The square root of 21442439 is about 4630.5981255125. The cubic root of 21442439 is about 277.8165162625.

It can be divided in two parts, 2 and 1442439, that added together give a palindrome (1442441).

The spelling of 21442439 in words is "twenty-one million, four hundred forty-two thousand, four hundred thirty-nine".