21445339 has 4 divisors (see below), whose sum is σ = 21473856. Its totient is φ = 21416824.

The previous prime is 21445331. The next prime is 21445349. The reversal of 21445339 is 93354412.

It is a semiprime because it is the product of two primes.

It is a cyclic number.

It is not a de Polignac number, because 21445339 - 2³ = 21445331 is a prime.

It is a Duffinian number.

It is a self number, because there is not a number n which added to its sum of digits gives 21445339.

It is not an unprimeable number, because it can be changed into a prime (21445331) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 13099 + ... + 14644.

It is an arithmetic number, because the mean of its divisors is an integer number (5368464).

Almost surely, 2^21445339 is an apocalyptic number.

21445339 is a deficient number, since it is larger than the sum of its proper divisors (28517).

21445339 is an equidigital number, since it uses as much as digits as its factorization.

21445339 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 28516.

The product of its digits is 12960, while the sum is 31.

The square root of 21445339 is about 4630.9112494195. The cubic root of 21445339 is about 277.8290402044.

The spelling of 21445339 in words is "twenty-one million, four hundred forty-five thousand, three hundred thirty-nine".