21685300638 has 16 divisors (see below), whose sum is σ = 43646849040. Its totient is φ = 7182392256.

The previous prime is 21685300621. The next prime is 21685300661. The reversal of 21685300638 is 83600358612.

21685300638 is digitally balanced in base 5, because in such base it contains all the possibile digits an equal number of times.

It is a Curzon number.

It is a self number, because there is not a number n which added to its sum of digits gives 21685300638.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 11509303 + ... + 11511186.

It is an arithmetic number, because the mean of its divisors is an integer number (2727928065).

Almost surely, 2^21685300638 is an apocalyptic number.

21685300638 is an abundant number, since it is smaller than the sum of its proper divisors (21961548402).

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

21685300638 is a wasteful number, since it uses less digits than its factorization.

21685300638 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 23020651.

The product of its (nonzero) digits is 207360, while the sum is 42.

The spelling of 21685300638 in words is "twenty-one billion, six hundred eighty-five million, three hundred thousand, six hundred thirty-eight".