21585004416 has 480 divisors, whose sum is σ = 69594069600. Its totient is φ = 6637842432.

The previous prime is 21585004387. The next prime is 21585004423. The reversal of 21585004416 is 61440058512.

It is a happy number.

21585004416 is a `hidden beast` number, since 21 + 585 + 0 + 0 + 44 + 16 = 666.

It is a Harshad number since it is a multiple of its sum of digits (36).

It is a congruent 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 59 ways as a sum of consecutive naturals, for example, 273227865 + ... + 273227943.

It is an arithmetic number, because the mean of its divisors is an integer number (144987645).

Almost surely, 2^21585004416 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 21585004416, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (34797034800).

21585004416 is an abundant number, since it is smaller than the sum of its proper divisors (48009065184).

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

21585004416 is an equidigital number, since it uses as much as digits as its factorization.

21585004416 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 216 (or 176 counting only the distinct ones).

The product of its (nonzero) digits is 38400, while the sum is 36.

The spelling of 21585004416 in words is "twenty-one billion, five hundred eighty-five million, four thousand, four hundred sixteen".