21606853800 has 432 divisors, whose sum is σ = 82802468160. Its totient is φ = 4646369280.

The previous prime is 21606853769. The next prime is 21606853831. The reversal of 21606853800 is 835860612.

It is a happy number.

It is an interprime number because it is at equal distance from previous prime (21606853769) and next prime (21606853831).

It is a super-2 number, since 2×21606853800² (a number of 21 digits) contains 22 as substring.

It is a hoax number, since the sum of its digits (39) coincides with the sum of the digits of its distinct prime factors.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 107 ways as a sum of consecutive naturals, for example, 8495329 + ... + 8497871.

It is an arithmetic number, because the mean of its divisors is an integer number (191672380).

Almost surely, 2^21606853800 is an apocalyptic number.

21606853800 is a gapful number since it is divisible by the number (20) formed by its first and last digit.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 21606853800, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (41401234080).

21606853800 is an abundant number, since it is smaller than the sum of its proper divisors (61195614360).

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

21606853800 is a wasteful number, since it uses less digits than its factorization.

21606853800 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 2610 (or 2577 counting only the distinct ones).

The product of its (nonzero) digits is 69120, while the sum is 39.

The spelling of 21606853800 in words is "twenty-one billion, six hundred six million, eight hundred fifty-three thousand, eight hundred".