21209648 has 20 divisors (see below), whose sum is σ = 41460888. Its totient is φ = 10510080.

The previous prime is 21209633. The next prime is 21209653. The reversal of 21209648 is 84690212.

It is an unprimeable number.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 4058 + ... + 7673.

Almost surely, 2^21209648 is an apocalyptic number.

It is an amenable number.

21209648 is a deficient number, since it is larger than the sum of its proper divisors (20251240).

21209648 is a wasteful number, since it uses less digits than its factorization.

21209648 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 11852 (or 11846 counting only the distinct ones).

The product of its (nonzero) digits is 6912, while the sum is 32.

The square root of 21209648 is about 4605.3933599639. The cubic root of 21209648 is about 276.8074791657.

The spelling of 21209648 in words is "twenty-one million, two hundred nine thousand, six hundred forty-eight".