21013684 has 12 divisors (see below), whose sum is σ = 37240000. Its totient is φ = 10373688.

The previous prime is 21013633. The next prime is 21013709. The reversal of 21013684 is 48631012.

It is a congruent number.

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, 32934 + ... + 33565.

Almost surely, 2^21013684 is an apocalyptic number.

It is an amenable number.

21013684 is a deficient number, since it is larger than the sum of its proper divisors (16226316).

21013684 is a wasteful number, since it uses less digits than its factorization.

21013684 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 66582 (or 66580 counting only the distinct ones).

The product of its (nonzero) digits is 1152, while the sum is 25.

The square root of 21013684 is about 4584.0684986156. The cubic root of 21013684 is about 275.9523302114.

Adding to 21013684 its reverse (48631012), we get a palindrome (69644696).

The spelling of 21013684 in words is "twenty-one million, thirteen thousand, six hundred eighty-four".