21856179912 has 96 divisors (see below), whose sum is σ = 63593449920. Its totient is φ = 6241468800.

The previous prime is 21856179907. The next prime is 21856179913. The reversal of 21856179912 is 21997165812.

It is not an unprimeable number, because it can be changed into a prime (21856179913) by changing a digit.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 3333037 + ... + 3339587.

It is an arithmetic number, because the mean of its divisors is an integer number (662431770).

Almost surely, 2^21856179912 is an apocalyptic number.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 21856179912, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (31796724960).

21856179912 is an abundant number, since it is smaller than the sum of its proper divisors (41737270008).

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

21856179912 is a wasteful number, since it uses less digits than its factorization.

21856179912 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 9411 (or 9400 counting only the distinct ones).

The product of its digits is 544320, while the sum is 51.

The spelling of 21856179912 in words is "twenty-one billion, eight hundred fifty-six million, one hundred seventy-nine thousand, nine hundred twelve".