21243359 has 2 divisors, whose sum is σ = 21243360. Its totient is φ = 21243358.

The previous prime is 21243347. The next prime is 21243361. The reversal of 21243359 is 95334212.

It is a strong prime.

It is a cyclic number.

It is not a de Polignac number, because 21243359 - 2¹⁶ = 21177823 is a prime.

Together with 21243361, 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 (21243059) 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, 10621679 + 10621680.

It is an arithmetic number, because the mean of its divisors is an integer number (10621680).

Almost surely, 2^21243359 is an apocalyptic number.

21243359 is a deficient number, since it is larger than the sum of its proper divisors (1).

21243359 is an equidigital number, since it uses as much as digits as its factorization.

21243359 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 6480, while the sum is 29.

The square root of 21243359 is about 4609.0518547745. The cubic root of 21243359 is about 276.9540558153.

The spelling of 21243359 in words is "twenty-one million, two hundred forty-three thousand, three hundred fifty-nine".