21953719872 has 448 divisors, whose sum is σ = 76905185280. Its totient is φ = 6009292800.

The previous prime is 21953719871. The next prime is 21953719883. The reversal of 21953719872 is 27891735912.

It is a happy number.

21953719872 is a `hidden beast` number, since 2 + 19 + 537 + 1 + 98 + 7 + 2 = 666.

It is a tau number, because it is divible by the number of its divisors (448).

It is a Harshad number since it is a multiple of its sum of digits (54).

It is not an unprimeable number, because it can be changed into a prime (21953719871) by changing a digit.

It is a polite number, since it can be written in 63 ways as a sum of consecutive naturals, for example, 47621722 + ... + 47622182.

It is an arithmetic number, because the mean of its divisors is an integer number (171663360).

Almost surely, 2^21953719872 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 21953719872, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (38452592640).

21953719872 is an abundant number, since it is smaller than the sum of its proper divisors (54951465408).

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

21953719872 is a wasteful number, since it uses less digits than its factorization.

21953719872 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 647 (or 631 counting only the distinct ones).

The product of its digits is 1905120, while the sum is 54.

The spelling of 21953719872 in words is "twenty-one billion, nine hundred fifty-three million, seven hundred nineteen thousand, eight hundred seventy-two".