21067439 has 2 divisors, whose sum is σ = 21067440. Its totient is φ = 21067438.

The previous prime is 21067433. The next prime is 21067441. The reversal of 21067439 is 93476012.

It is a strong prime.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-21067439 is a prime.

Together with 21067441, 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 (21067433) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10533719 + 10533720.

It is an arithmetic number, because the mean of its divisors is an integer number (10533720).

Almost surely, 2^21067439 is an apocalyptic number.

21067439 is a deficient number, since it is larger than the sum of its proper divisors (1).

21067439 is an equidigital number, since it uses as much as digits as its factorization.

21067439 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 9072, while the sum is 32.

The square root of 21067439 is about 4589.9279950779. The cubic root of 21067439 is about 276.1874339448.

The spelling of 21067439 in words is "twenty-one million, sixty-seven thousand, four hundred thirty-nine".