21500520000000 has 640 divisors, whose sum is σ = 72169268371200. Its totient is φ = 5687808000000.

The previous prime is 21500519999951. The next prime is 21500520000073. The reversal of 21500520000000 is 2500512.

It is a tau number, because it is divible by the number of its divisors (640).

It is a super-4 number, since 4×21500520000000⁴ (a number of 54 digits) contains 4444 as substring.

It is a Harshad number since it is a multiple of its sum of digits (15).

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (23) of ones.

It is a polite number, since it can be written in 63 ways as a sum of consecutive naturals, for example, 16679999356 + ... + 16680000644.

It is an arithmetic number, because the mean of its divisors is an integer number (112764481830).

Almost surely, 2^{21500520000000} is an apocalyptic number.

21500520000000 is a gapful number since it is divisible by the number (20) 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 21500520000000, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (36084634185600).

21500520000000 is an abundant number, since it is smaller than the sum of its proper divisors (50668748371200).

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

21500520000000 is an frugal number, since it uses more digits than its factorization.

21500520000000 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1484 (or 1438 counting only the distinct ones).

The product of its (nonzero) digits is 100, while the sum is 15.

Adding to 21500520000000 its reverse (2500512), we get a palindrome (21500522500512).

The spelling of 21500520000000 in words is "twenty-one trillion, five hundred billion, five hundred twenty million", and thus it is an aban number.