21013444320 has 576 divisors, whose sum is σ = 78606775296. Its totient is φ = 4676485120.

The previous prime is 21013444313. The next prime is 21013444351. The reversal of 21013444320 is 2344431012.

It is a Harshad number since it is a multiple of its sum of digits (24).

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 95 ways as a sum of consecutive naturals, for example, 71718094 + ... + 71718386.

It is an arithmetic number, because the mean of its divisors is an integer number (136470096).

Almost surely, 2^21013444320 is an apocalyptic number.

21013444320 is a gapful number since it is divisible by the number (20) 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 21013444320, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (39303387648).

21013444320 is an abundant number, since it is smaller than the sum of its proper divisors (57593330976).

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

21013444320 is a wasteful number, since it uses less digits than its factorization.

21013444320 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 403 (or 378 counting only the distinct ones).

The product of its (nonzero) digits is 2304, while the sum is 24.

Adding to 21013444320 its reverse (2344431012), we get a palindrome (23357875332).

The spelling of 21013444320 in words is "twenty-one billion, thirteen million, four hundred forty-four thousand, three hundred twenty".