21806855910 has 384 divisors, whose sum is σ = 73618191360. Its totient is φ = 4483759104.

The previous prime is 21806855899. The next prime is 21806855957. The reversal of 21806855910 is 1955860812.

It is a happy number.

21806855910 is a `hidden beast` number, since 2 + 1 + 80 + 6 + 8 + 559 + 10 = 666.

It is a Harshad number since it is a multiple of its sum of digits (45).

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 191 ways as a sum of consecutive naturals, for example, 16996129 + ... + 16997411.

It is an arithmetic number, because the mean of its divisors is an integer number (191714040).

Almost surely, 2^21806855910 is an apocalyptic number.

It is a practical number, because each smaller number is the sum of distinct divisors of 21806855910, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (36809095680).

21806855910 is an abundant number, since it is smaller than the sum of its proper divisors (51811335450).

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

21806855910 is a wasteful number, since it uses less digits than its factorization.

21806855910 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1369 (or 1340 counting only the distinct ones).

The product of its (nonzero) digits is 172800, while the sum is 45.

The spelling of 21806855910 in words is "twenty-one billion, eight hundred six million, eight hundred fifty-five thousand, nine hundred ten".