21209308 has 6 divisors (see below), whose sum is σ = 37116296. Its totient is φ = 10604652.

The previous prime is 21209231. The next prime is 21209311. The reversal of 21209308 is 80390212.

It is a congruent number.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 2651160 + ... + 2651167.

Almost surely, 2^21209308 is an apocalyptic number.

It is an amenable number.

21209308 is a deficient number, since it is larger than the sum of its proper divisors (15906988).

21209308 is a wasteful number, since it uses less digits than its factorization.

21209308 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 5302331 (or 5302329 counting only the distinct ones).

The product of its (nonzero) digits is 864, while the sum is 25.

The square root of 21209308 is about 4605.3564465739. The cubic root of 21209308 is about 276.8060000426.

The spelling of 21209308 in words is "twenty-one million, two hundred nine thousand, three hundred eight".