21064443400 has 288 divisors, whose sum is σ = 66935090880. Its totient is φ = 6060096000.

The previous prime is 21064443391. The next prime is 21064443403. The reversal of 21064443400 is 434446012.

It is a Harshad number since it is a multiple of its sum of digits (28).

It is not an unprimeable number, because it can be changed into a prime (21064443403) by changing a digit.

It is a polite number, since it can be written in 71 ways as a sum of consecutive naturals, for example, 1393885 + ... + 1408915.

It is an arithmetic number, because the mean of its divisors is an integer number (232413510).

Almost surely, 2^21064443400 is an apocalyptic number.

21064443400 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 21064443400, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (33467545440).

21064443400 is an abundant number, since it is smaller than the sum of its proper divisors (45870647480).

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

21064443400 is a wasteful number, since it uses less digits than its factorization.

21064443400 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 15085 (or 15069 counting only the distinct ones).

The product of its (nonzero) digits is 9216, while the sum is 28.

Adding to 21064443400 its reverse (434446012), we get a palindrome (21498889412).

It can be divided in two parts, 21064 and 443400, that added together give a palindrome (464464).

The spelling of 21064443400 in words is "twenty-one billion, sixty-four million, four hundred forty-three thousand, four hundred".