21558635628 has 12 divisors (see below), whose sum is σ = 50303483160. Its totient is φ = 7186211872.

The previous prime is 21558635611. The next prime is 21558635639. The reversal of 21558635628 is 82653685512.

It is a happy number.

It is a tau number, because it is divible by the number of its divisors (12).

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, 898276473 + ... + 898276496.

It is an arithmetic number, because the mean of its divisors is an integer number (4191956930).

Almost surely, 2^21558635628 is an apocalyptic number.

It is an amenable number.

21558635628 is an abundant number, since it is smaller than the sum of its proper divisors (28744847532).

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

21558635628 is a wasteful number, since it uses less digits than its factorization.

21558635628 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1796552976 (or 1796552974 counting only the distinct ones).

The product of its digits is 3456000, while the sum is 51.

The spelling of 21558635628 in words is "twenty-one billion, five hundred fifty-eight million, six hundred thirty-five thousand, six hundred twenty-eight".