21531543542520 has 64 divisors (see below), whose sum is σ = 70466869779840. Its totient is φ = 5219768131200.

The previous prime is 21531543542519. The next prime is 21531543542527. The reversal of 21531543542520 is 2524534513512.

It is a super-2 number, since 2×21531543542520² (a number of 27 digits) contains 22 as substring.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21531543542527) by changing a digit.

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 15 ways as a sum of consecutive naturals, for example, 8155886386 + ... + 8155889025.

It is an arithmetic number, because the mean of its divisors is an integer number (1101044840310).

Almost surely, 2^{21531543542520} is an apocalyptic number.

21531543542520 is a gapful number since it is divisible by the number (20) formed by its first and last digit.

It is an amenable number.

21531543542520 is an abundant number, since it is smaller than the sum of its proper divisors (48935326237320).

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

21531543542520 is a wasteful number, since it uses less digits than its factorization.

21531543542520 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 16311775436 (or 16311775432 counting only the distinct ones).

The product of its (nonzero) digits is 720000, while the sum is 42.

The spelling of 21531543542520 in words is "twenty-one trillion, five hundred thirty-one billion, five hundred forty-three million, five hundred forty-two thousand, five hundred twenty".