21020034400 has 144 divisors (see below), whose sum is σ = 54116067600. Its totient is φ = 7950735360.

The previous prime is 21020034377. The next prime is 21020034401. The reversal of 21020034400 is 443002012.

It is a Harshad number since it is a multiple of its sum of digits (16).

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21020034401) by changing a digit.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 11748706 + ... + 11750494.

It is an arithmetic number, because the mean of its divisors is an integer number (375806025).

Almost surely, 2^21020034400 is an apocalyptic number.

21020034400 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 21020034400, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (27058033800).

21020034400 is an abundant number, since it is smaller than the sum of its proper divisors (33096033200).

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

21020034400 is a wasteful number, since it uses less digits than its factorization.

21020034400 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 2601 (or 2588 counting only the distinct ones).

The product of its (nonzero) digits is 192, while the sum is 16.

Adding to 21020034400 its reverse (443002012), we get a palindrome (21463036412).

The spelling of 21020034400 in words is "twenty-one billion, twenty million, thirty-four thousand, four hundred".