21668883264 has 448 divisors, whose sum is σ = 77669867520. Its totient is φ = 5782855680.

The previous prime is 21668883263. The next prime is 21668883287. The reversal of 21668883264 is 46238886612.

It is a tau number, because it is divible by the number of its divisors (448).

It is a Harshad number since it is a multiple of its sum of digits (54).

It is a nude number because it is divisible by every one of its digits.

It is a self number, because there is not a number n which added to its sum of digits gives 21668883264.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21668883263) by changing a digit.

It is a polite number, since it can be written in 63 ways as a sum of consecutive naturals, for example, 34340229 + ... + 34340859.

It is an arithmetic number, because the mean of its divisors is an integer number (173370240).

Almost surely, 2^21668883264 is an apocalyptic number.

21668883264 is a gapful number since it is divisible by the number (24) formed by its first and last digit.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 21668883264, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (38834933760).

21668883264 is an abundant number, since it is smaller than the sum of its proper divisors (56000984256).

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

21668883264 is a wasteful number, since it uses less digits than its factorization.

21668883264 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 843 (or 827 counting only the distinct ones).

The product of its digits is 5308416, while the sum is 54.

The spelling of 21668883264 in words is "twenty-one billion, six hundred sixty-eight million, eight hundred eighty-three thousand, two hundred sixty-four".