21585649487472 has 1600 divisors, whose sum is σ = 77166112302720. Its totient is φ = 5769617817600.

The previous prime is 21585649487443. The next prime is 21585649487491. The reversal of 21585649487472 is 27478494658512.

21585649487472 is a `hidden beast` number, since 2 + 1 + 5 + 8 + 5 + 64 + 94 + 8 + 7 + 472 = 666.

It is a Harshad number since it is a multiple of its sum of digits (72).

It is a self number, because there is not a number n which added to its sum of digits gives 21585649487472.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 319 ways as a sum of consecutive naturals, for example, 137488213218 + ... + 137488213374.

Almost surely, 2^{21585649487472} 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 21585649487472, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (38583056151360).

21585649487472 is an abundant number, since it is smaller than the sum of its proper divisors (55580462815248).

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

21585649487472 is a wasteful number, since it uses less digits than its factorization.

21585649487472 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 357 (or 324 counting only the distinct ones).

The product of its digits is 1083801600, while the sum is 72.

The spelling of 21585649487472 in words is "twenty-one trillion, five hundred eighty-five billion, six hundred forty-nine million, four hundred eighty-seven thousand, four hundred seventy-two".