21585458664 has 192 divisors, whose sum is σ = 75585968640. Its totient is φ = 5606573760.

The previous prime is 21585458651. The next prime is 21585458683. The reversal of 21585458664 is 46685458512.

21585458664 is a `hidden beast` number, since 2 + 1 + 5 + 8 + 54 + 586 + 6 + 4 = 666.

It is a Harshad number since it is a multiple of its sum of digits (54).

It is a self number, because there is not a number n which added to its sum of digits gives 21585458664.

It is an unprimeable number.

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 47 ways as a sum of consecutive naturals, for example, 77587 + ... + 221789.

It is an arithmetic number, because the mean of its divisors is an integer number (393676920).

Almost surely, 2^21585458664 is an apocalyptic number.

21585458664 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 21585458664, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (37792984320).

21585458664 is an abundant number, since it is smaller than the sum of its proper divisors (54000509976).

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

21585458664 is a wasteful number, since it uses less digits than its factorization.

21585458664 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 144242 (or 144226 counting only the distinct ones).

The product of its digits is 9216000, while the sum is 54.

It can be divided in two parts, 21585 and 458664, that added together give a square (480249 = 693²).

The spelling of 21585458664 in words is "twenty-one billion, five hundred eighty-five million, four hundred fifty-eight thousand, six hundred sixty-four".