21432239 has 2 divisors, whose sum is σ = 21432240. Its totient is φ = 21432238.

The previous prime is 21432233. The next prime is 21432241. The reversal of 21432239 is 93223412.

It is a strong prime.

It is a cyclic number.

It is not a de Polignac number, because 21432239 - 2⁸ = 21431983 is a prime.

Together with 21432241, 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 (21432233) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10716119 + 10716120.

It is an arithmetic number, because the mean of its divisors is an integer number (10716120).

Almost surely, 2^21432239 is an apocalyptic number.

21432239 is a deficient number, since it is larger than the sum of its proper divisors (1).

21432239 is an equidigital number, since it uses as much as digits as its factorization.

21432239 is an evil number, because the sum of its binary digits is even.

The product of its digits is 2592, while the sum is 26.

The square root of 21432239 is about 4629.4966249043. The cubic root of 21432239 is about 277.7724575633.

The spelling of 21432239 in words is "twenty-one million, four hundred thirty-two thousand, two hundred thirty-nine".