21505200516 has 96 divisors (see below), whose sum is σ = 57134246400. Its totient is φ = 6992837280.

The previous prime is 21505200487. The next prime is 21505200527. The reversal of 21505200516 is 61500250512.

It is a Harshad number since it is a multiple of its sum of digits (27).

It is a self number, because there is not a number n which added to its sum of digits gives 21505200516.

It is an unprimeable number.

It is a polite number, since it can be written in 31 ways as a sum of consecutive naturals, for example, 821851 + ... + 847613.

It is an arithmetic number, because the mean of its divisors is an integer number (595148400).

Almost surely, 2^21505200516 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 21505200516, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (28567123200).

21505200516 is an abundant number, since it is smaller than the sum of its proper divisors (35629045884).

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

21505200516 is a wasteful number, since it uses less digits than its factorization.

21505200516 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 25966 (or 25958 counting only the distinct ones).

The product of its (nonzero) digits is 3000, while the sum is 27.

The spelling of 21505200516 in words is "twenty-one billion, five hundred five million, two hundred thousand, five hundred sixteen".