21630961728 has 84 divisors (see below), whose sum is σ = 64139269740. Its totient is φ = 6961683456.

The previous prime is 21630961727. The next prime is 21630961769. The reversal of 21630961728 is 82716903612.

21630961728 is a `hidden beast` number, since 2 + 1 + 6 + 3 + 0 + 9 + 617 + 28 = 666.

It can be written as a sum of positive squares in 2 ways, for example, as 11212268544 + 10418693184 = 105888^2 + 102072^2 .

It is not an unprimeable number, because it can be changed into a prime (21630961727) 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 11 ways as a sum of consecutive naturals, for example, 630775 + ... + 664182.

It is an arithmetic number, because the mean of its divisors is an integer number (763562735).

Almost surely, 2^21630961728 is an apocalyptic number.

It is an amenable number.

21630961728 is an abundant number, since it is smaller than the sum of its proper divisors (42508308012).

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

21630961728 is a wasteful number, since it uses less digits than its factorization.

21630961728 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1295004 (or 1294991 counting only the distinct ones).

The product of its (nonzero) digits is 217728, while the sum is 45.

The spelling of 21630961728 in words is "twenty-one billion, six hundred thirty million, nine hundred sixty-one thousand, seven hundred twenty-eight".