21759561984 has 144 divisors (see below), whose sum is σ = 60166399104. Its totient is φ = 6975897600.

The previous prime is 21759561979. The next prime is 21759561997. The reversal of 21759561984 is 48916595712.

It is a happy number.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 2230782 + ... + 2240514.

It is an arithmetic number, because the mean of its divisors is an integer number (417822216).

Almost surely, 2^21759561984 is an apocalyptic number.

21759561984 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 21759561984, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (30083199552).

21759561984 is an abundant number, since it is smaller than the sum of its proper divisors (38406837120).

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

21759561984 is an equidigital number, since it uses as much as digits as its factorization.

21759561984 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 9864 (or 9850 counting only the distinct ones).

The product of its digits is 5443200, while the sum is 57.

The spelling of 21759561984 in words is "twenty-one billion, seven hundred fifty-nine million, five hundred sixty-one thousand, nine hundred eighty-four".