21909339 has 8 divisors (see below), whose sum is σ = 32458320. Its totient is φ = 14606208.

The previous prime is 21909331. The next prime is 21909341. The reversal of 21909339 is 93390912.

It is not a de Polignac number, because 21909339 - 2³ = 21909331 is a prime.

It is not an unprimeable number, because it can be changed into a prime (21909331) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 405702 + ... + 405755.

It is an arithmetic number, because the mean of its divisors is an integer number (4057290).

Almost surely, 2^21909339 is an apocalyptic number.

21909339 is a deficient number, since it is larger than the sum of its proper divisors (10548981).

21909339 is an equidigital number, since it uses as much as digits as its factorization.

21909339 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 811466 (or 811460 counting only the distinct ones).

The product of its (nonzero) digits is 13122, while the sum is 36.

The square root of 21909339 is about 4680.7412874458. The cubic root of 21909339 is about 279.8185005725.

The spelling of 21909339 in words is "twenty-one million, nine hundred nine thousand, three hundred thirty-nine".