21001443320 has 128 divisors (see below), whose sum is σ = 55724760000. Its totient is φ = 7022714880.

The previous prime is 21001443311. The next prime is 21001443347. The reversal of 21001443320 is 2334410012.

It is a Harshad number since it is a multiple of its sum of digits (20).

It is a junction number, because it is equal to n+sod(n) for n = 21001443292 and 21001443301.

It is a congruent number.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (19) of ones.

It is a polite number, since it can be written in 31 ways as a sum of consecutive naturals, for example, 1531856 + ... + 1545504.

Almost surely, 2^21001443320 is an apocalyptic number.

21001443320 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 21001443320, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (27862380000).

21001443320 is an abundant number, since it is smaller than the sum of its proper divisors (34723316680).

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

21001443320 is a wasteful number, since it uses less digits than its factorization.

21001443320 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 13953 (or 13949 counting only the distinct ones).

The product of its (nonzero) digits is 576, while the sum is 20.

Adding to 21001443320 its reverse (2334410012), we get a palindrome (23335853332).

The spelling of 21001443320 in words is "twenty-one billion, one million, four hundred forty-three thousand, three hundred twenty".