21453239 has 2 divisors, whose sum is σ = 21453240. Its totient is φ = 21453238.

The previous prime is 21453203. The next prime is 21453247. The reversal of 21453239 is 93235412.

It is a strong prime.

It is a cyclic number.

It is not a de Polignac number, because 21453239 - 2¹² = 21449143 is a prime.

It is a super-2 number, since 2×21453239² = 920482927182242, which contains 22 as substring.

It is a Chen prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (21450239) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10726619 + 10726620.

It is an arithmetic number, because the mean of its divisors is an integer number (10726620).

Almost surely, 2^21453239 is an apocalyptic number.

21453239 is a deficient number, since it is larger than the sum of its proper divisors (1).

21453239 is an equidigital number, since it uses as much as digits as its factorization.

21453239 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 21453239 is about 4631.7641347547. The cubic root of 21453239 is about 277.8631514233.

The spelling of 21453239 in words is "twenty-one million, four hundred fifty-three thousand, two hundred thirty-nine".