21981104565504 has 288 divisors, whose sum is σ = 70978985118720. Its totient is φ = 5895279968256.

The previous prime is 21981104565503. The next prime is 21981104565533. The reversal of 21981104565504 is 40556540118912.

It is a Harshad number since it is a multiple of its sum of digits (51).

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21981104565503) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (29) of ones.

It is a polite number, since it can be written in 31 ways as a sum of consecutive naturals, for example, 34320267 + ... + 34954869.

It is an arithmetic number, because the mean of its divisors is an integer number (246454809440).

Almost surely, 2^{21981104565504} is an apocalyptic number.

21981104565504 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 21981104565504, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (35489492559360).

21981104565504 is an abundant number, since it is smaller than the sum of its proper divisors (48997880553216).

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

21981104565504 is a wasteful number, since it uses less digits than its factorization.

21981104565504 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 635025 (or 635011 counting only the distinct ones).

The product of its (nonzero) digits is 1728000, while the sum is 51.

The spelling of 21981104565504 in words is "twenty-one trillion, nine hundred eighty-one billion, one hundred four million, five hundred sixty-five thousand, five hundred four".