21375728 has 20 divisors (see below), whose sum is σ = 45180888. Its totient is φ = 9716160.

The previous prime is 21375721. The next prime is 21375743. The reversal of 21375728 is 82757312.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21375721) by changing a digit.

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 3 ways as a sum of consecutive naturals, for example, 60551 + ... + 60902.

Almost surely, 2^21375728 is an apocalyptic number.

It is an amenable number.

21375728 is an abundant number, since it is smaller than the sum of its proper divisors (23805160).

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

21375728 is a wasteful number, since it uses less digits than its factorization.

21375728 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 121472 (or 121466 counting only the distinct ones).

The product of its digits is 23520, while the sum is 35.

The square root of 21375728 is about 4623.3892330194. The cubic root of 21375728 is about 277.5281058025.

The spelling of 21375728 in words is "twenty-one million, three hundred seventy-five thousand, seven hundred twenty-eight".