21516587136 has 192 divisors, whose sum is σ = 69725111040. Its totient is φ = 6309734400.

The previous prime is 21516587129. The next prime is 21516587159. The reversal of 21516587136 is 63178561512.

21516587136 is a `hidden beast` number, since 2 + 1 + 51 + 6 + 587 + 13 + 6 = 666.

It is a tau number, because it is divible by the number of its divisors (192).

It is a junction number, because it is equal to n+sod(n) for n = 21516587091 and 21516587100.

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 23 ways as a sum of consecutive naturals, for example, 365446 + ... + 420218.

It is an arithmetic number, because the mean of its divisors is an integer number (363151620).

Almost surely, 2^21516587136 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 21516587136, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (34862555520).

21516587136 is an abundant number, since it is smaller than the sum of its proper divisors (48208523904).

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

21516587136 is a wasteful number, since it uses less digits than its factorization.

21516587136 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 54835 (or 54820 counting only the distinct ones).

The product of its digits is 302400, while the sum is 45.

The spelling of 21516587136 in words is "twenty-one billion, five hundred sixteen million, five hundred eighty-seven thousand, one hundred thirty-six".