21956571504 has 200 divisors, whose sum is σ = 74110757600. Its totient is φ = 6273179136.

The previous prime is 21956571473. The next prime is 21956571509. The reversal of 21956571504 is 40517565912.

It is a happy number.

21956571504 is a `hidden beast` number, since 2 + 1 + 95 + 6 + 57 + 1 + 504 = 666.

It is a self number, because there is not a number n which added to its sum of digits gives 21956571504.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21956571509) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written in 39 ways as a sum of consecutive naturals, for example, 419832 + ... + 469224.

It is an arithmetic number, because the mean of its divisors is an integer number (370553788).

Almost surely, 2^21956571504 is an apocalyptic number.

21956571504 is a gapful number since it is divisible by the number (24) 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 21956571504, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (37055378800).

21956571504 is an abundant number, since it is smaller than the sum of its proper divisors (52154186096).

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

21956571504 is an equidigital number, since it uses as much as digits as its factorization.

21956571504 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 49434 (or 49405 counting only the distinct ones).

The product of its (nonzero) digits is 378000, while the sum is 45.

The spelling of 21956571504 in words is "twenty-one billion, nine hundred fifty-six million, five hundred seventy-one thousand, five hundred four".