21643958336 has 224 divisors, whose sum is σ = 58129505280. Its totient is φ = 7721625600.

The previous prime is 21643958321. The next prime is 21643958353. The reversal of 21643958336 is 63385934612.

It is a tau number, because it is divible by the number of its divisors (224).

It is an unprimeable number.

It is a polite number, since it can be written in 31 ways as a sum of consecutive naturals, for example, 8391095 + ... + 8393673.

It is an arithmetic number, because the mean of its divisors is an integer number (259506720).

Almost surely, 2^21643958336 is an apocalyptic number.

21643958336 is a gapful number since it is divisible by the number (26) 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 21643958336, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (29064752640).

21643958336 is an abundant number, since it is smaller than the sum of its proper divisors (36485546944).

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

21643958336 is a wasteful number, since it uses less digits than its factorization.

21643958336 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 2753 (or 2743 counting only the distinct ones).

The product of its digits is 2799360, while the sum is 50.

It can be divided in two parts, 21643 and 958336, that added together give a palindrome (979979).

The spelling of 21643958336 in words is "twenty-one billion, six hundred forty-three million, nine hundred fifty-eight thousand, three hundred thirty-six".