21561184638252 has 288 divisors, whose sum is σ = 64931313807360. Its totient is φ = 5904631313280.

The previous prime is 21561184638251. The next prime is 21561184638283. The reversal of 21561184638252 is 25283648116512.

21561184638252 is a `hidden beast` number, since 2 + 1 + 56 + 1 + 1 + 8 + 463 + 82 + 52 = 666.

It is not an unprimeable number, because it can be changed into a prime (21561184638251) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (19) of ones.

It is a polite number, since it can be written in 95 ways as a sum of consecutive naturals, for example, 365024473 + ... + 365083535.

It is an arithmetic number, because the mean of its divisors is an integer number (225455950720).

Almost surely, 2^{21561184638252} 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 21561184638252, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (32465656903680).

21561184638252 is an abundant number, since it is smaller than the sum of its proper divisors (43370129169108).

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

21561184638252 is a wasteful number, since it uses less digits than its factorization.

21561184638252 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 59753 (or 59748 counting only the distinct ones).

The product of its digits is 5529600, while the sum is 54.

The spelling of 21561184638252 in words is "twenty-one trillion, five hundred sixty-one billion, one hundred eighty-four million, six hundred thirty-eight thousand, two hundred fifty-two".