21728284 has 24 divisors (see below), whose sum is σ = 40360320. Its totient is φ = 10213104.

The previous prime is 21728269. The next prime is 21728293. The reversal of 21728284 is 48282712.

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, 3427 + ... + 7429.

It is an arithmetic number, because the mean of its divisors is an integer number (1681680).

Almost surely, 2^21728284 is an apocalyptic number.

It is an amenable number.

21728284 is a deficient number, since it is larger than the sum of its proper divisors (18632036).

21728284 is a wasteful number, since it uses less digits than its factorization.

21728284 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 4089 (or 4087 counting only the distinct ones).

The product of its digits is 14336, while the sum is 34.

The square root of 21728284 is about 4661.3607455334. The cubic root of 21728284 is about 279.0455769292.

The spelling of 21728284 in words is "twenty-one million, seven hundred twenty-eight thousand, two hundred eighty-four".