21530167728 has 20 divisors (see below), whose sum is σ = 55619600088. Its totient is φ = 7176722560.

The previous prime is 21530167721. The next prime is 21530167739. The reversal of 21530167728 is 82776103512.

It is a self number, because there is not a number n which added to its sum of digits gives 21530167728.

It is not an unprimeable number, because it can be changed into a prime (21530167721) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 224272533 + ... + 224272628.

Almost surely, 2^21530167728 is an apocalyptic number.

It is an amenable number.

21530167728 is an abundant number, since it is smaller than the sum of its proper divisors (34089432360).

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

21530167728 is a wasteful number, since it uses less digits than its factorization.

21530167728 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 448545172 (or 448545166 counting only the distinct ones).

The product of its (nonzero) digits is 141120, while the sum is 42.

The spelling of 21530167728 in words is "twenty-one billion, five hundred thirty million, one hundred sixty-seven thousand, seven hundred twenty-eight".