21444239 has 2 divisors, whose sum is σ = 21444240. Its totient is φ = 21444238.

The previous prime is 21444233. The next prime is 21444251. The reversal of 21444239 is 93244412.

It is a weak prime.

It is a cyclic number.

It is not a de Polignac number, because 21444239 - 2⁴ = 21444223 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (21444233) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10722119 + 10722120.

It is an arithmetic number, because the mean of its divisors is an integer number (10722120).

Almost surely, 2^21444239 is an apocalyptic number.

21444239 is a deficient number, since it is larger than the sum of its proper divisors (1).

21444239 is an equidigital number, since it uses as much as digits as its factorization.

21444239 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 21444239 is about 4630.7924807748. The cubic root of 21444239 is about 277.8242898766.

The spelling of 21444239 in words is "twenty-one million, four hundred forty-four thousand, two hundred thirty-nine".