21518647454976 has 72 divisors (see below), whose sum is σ = 65452552691904. Its totient is φ = 6148184985600.

The previous prime is 21518647454911. The next prime is 21518647454977. The reversal of 21518647454976 is 67945474681512.

It is a self number, because there is not a number n which added to its sum of digits gives 21518647454976.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21518647454977) 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 7 ways as a sum of consecutive naturals, for example, 2001356925 + ... + 2001367676.

It is an arithmetic number, because the mean of its divisors is an integer number (909063231832).

Almost surely, 2^{21518647454976} is an apocalyptic number.

It is an amenable number.

21518647454976 is an abundant number, since it is smaller than the sum of its proper divisors (43933905236928).

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

21518647454976 is an equidigital number, since it uses as much as digits as its factorization.

21518647454976 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 4002724627 (or 4002724613 counting only the distinct ones).

The product of its digits is 406425600, while the sum is 69.

The spelling of 21518647454976 in words is "twenty-one trillion, five hundred eighteen billion, six hundred forty-seven million, four hundred fifty-four thousand, nine hundred seventy-six".