21664407486016 has 63 divisors (see below), whose sum is σ = 43928006047419. Its totient is φ = 10600874894208.

The previous prime is 21664407486011. The next prime is 21664407486037. The reversal of 21664407486016 is 61068470446612.

The square root of 21664407486016 is 4654504.

It is a perfect power (a square), and thus also a powerful number.

It is a super-2 number, since 2×21664407486016² (a number of 27 digits) contains 22 as substring.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (21664407486011) by changing a digit.

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 8 ways as a sum of consecutive naturals, for example, 1750087315 + ... + 1750099693.

Almost surely, 2^{21664407486016} is an apocalyptic number.

21664407486016 is the 4654504-th square number.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 21664407486016

21664407486016 is an abundant number, since it is smaller than the sum of its proper divisors (22263598561403).

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

21664407486016 is an frugal number, since it uses more digits than its factorization.

21664407486016 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 24864 (or 12428 counting only the distinct ones).

The product of its (nonzero) digits is 9289728, while the sum is 55.

The spelling of 21664407486016 in words is "twenty-one trillion, six hundred sixty-four billion, four hundred seven million, four hundred eighty-six thousand, sixteen".