21665288448 has 216 divisors, whose sum is σ = 66004848000. Its totient is φ = 6823391232.

The previous prime is 21665288399. The next prime is 21665288467. The reversal of 21665288448 is 84488256612.

It is a junction number, because it is equal to n+sod(n) for n = 21665288394 and 21665288403.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 3136903 + ... + 3143801.

It is an arithmetic number, because the mean of its divisors is an integer number (305578000).

Almost surely, 2^21665288448 is an apocalyptic number.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 21665288448, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (33002424000).

21665288448 is an abundant number, since it is smaller than the sum of its proper divisors (44339559552).

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

21665288448 is a wasteful number, since it uses less digits than its factorization.

21665288448 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 6997 (or 6980 counting only the distinct ones).

The product of its digits is 5898240, while the sum is 54.

The spelling of 21665288448 in words is "twenty-one billion, six hundred sixty-five million, two hundred eighty-eight thousand, four hundred forty-eight".