21264728 has 32 divisors (see below), whose sum is σ = 40983600. Its totient is φ = 10340352.

The previous prime is 21264709. The next prime is 21264769. The reversal of 21264728 is 82746212.

It is a junction number, because it is equal to n+sod(n) for n = 21264694 and 21264703.

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 in 7 ways as a sum of consecutive naturals, for example, 51788 + ... + 52196.

Almost surely, 2^21264728 is an apocalyptic number.

It is an amenable number.

21264728 is a deficient number, since it is larger than the sum of its proper divisors (19718872).

21264728 is a wasteful number, since it uses less digits than its factorization.

21264728 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 579 (or 575 counting only the distinct ones).

The product of its digits is 10752, while the sum is 32.

The square root of 21264728 is about 4611.3694278381. The cubic root of 21264728 is about 277.0468887161.

The spelling of 21264728 in words is "twenty-one million, two hundred sixty-four thousand, seven hundred twenty-eight".