21657560128 has 28 divisors (see below), whose sum is σ = 43378386192. Its totient is φ = 10727573120.

The previous prime is 21657560117. The next prime is 21657560129. The reversal of 21657560128 is 82106575612.

It is not an unprimeable number, because it can be changed into a prime (21657560129) 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, 1574458 + ... + 1588153.

Almost surely, 2^21657560128 is an apocalyptic number.

It is an amenable number.

21657560128 is an abundant number, since it is smaller than the sum of its proper divisors (21720826064).

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

21657560128 is a wasteful number, since it uses less digits than its factorization.

21657560128 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 3162730 (or 3162720 counting only the distinct ones).

The product of its (nonzero) digits is 201600, while the sum is 43.

The spelling of 21657560128 in words is "twenty-one billion, six hundred fifty-seven million, five hundred sixty thousand, one hundred twenty-eight".