21663213136 has 80 divisors (see below), whose sum is σ = 44744457600. Its totient is φ = 10138258944.

The previous prime is 21663213097. The next prime is 21663213151. The reversal of 21663213136 is 63131236612.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 4969870 + ... + 4974226.

It is an arithmetic number, because the mean of its divisors is an integer number (559305720).

Almost surely, 2^21663213136 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 21663213136, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (22372228800).

21663213136 is an abundant number, since it is smaller than the sum of its proper divisors (23081244464).

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

21663213136 is a wasteful number, since it uses less digits than its factorization.

21663213136 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 4676 (or 4670 counting only the distinct ones).

The product of its digits is 23328, while the sum is 34.

Adding to 21663213136 its reverse (63131236612), we get a palindrome (84794449748).

The spelling of 21663213136 in words is "twenty-one billion, six hundred sixty-three million, two hundred thirteen thousand, one hundred thirty-six".