21452728 has 16 divisors (see below), whose sum is σ = 43880760. Its totient is φ = 9751200.

The previous prime is 21452701. The next prime is 21452731. The reversal of 21452728 is 82725412.

It is a happy number.

It is a self number, because there is not a number n which added to its sum of digits gives 21452728.

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, 121803 + ... + 121978.

Almost surely, 2^21452728 is an apocalyptic number.

It is an amenable number.

21452728 is an abundant number, since it is smaller than the sum of its proper divisors (22428032).

It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.

21452728 is a wasteful number, since it uses less digits than its factorization.

21452728 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 243798 (or 243794 counting only the distinct ones).

The product of its digits is 8960, while the sum is 31.

The square root of 21452728 is about 4631.7089718591. The cubic root of 21452728 is about 277.8609452421.

The spelling of 21452728 in words is "twenty-one million, four hundred fifty-two thousand, seven hundred twenty-eight".