21152521664440 has 64 divisors (see below), whose sum is σ = 47728901376000. Its totient is φ = 8436882437760.

The previous prime is 21152521664389. The next prime is 21152521664447. The reversal of 21152521664440 is 4446612525112.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21152521664447) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 268765495 + ... + 268844185.

It is an arithmetic number, because the mean of its divisors is an integer number (745764084000).

Almost surely, 2^{21152521664440} is an apocalyptic number.

21152521664440 is a gapful number since it is divisible by the number (20) formed by its first and last digit.

It is an amenable number.

21152521664440 is an abundant number, since it is smaller than the sum of its proper divisors (26576379711560).

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

21152521664440 is a wasteful number, since it uses less digits than its factorization.

21152521664440 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 97780 (or 97776 counting only the distinct ones).

The product of its (nonzero) digits is 460800, while the sum is 43.

The spelling of 21152521664440 in words is "twenty-one trillion, one hundred fifty-two billion, five hundred twenty-one million, six hundred sixty-four thousand, four hundred forty".