21513404400 has 120 divisors (see below), whose sum is σ = 69097898880. Its totient is φ = 5721649920.

The previous prime is 21513404371. The next prime is 21513404401. The reversal of 21513404400 is 440431512.

It is a tau number, because it is divible by the number of its divisors (120).

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

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21513404401) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 431149 + ... + 478451.

It is an arithmetic number, because the mean of its divisors is an integer number (575815824).

Almost surely, 2^21513404400 is an apocalyptic number.

21513404400 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 21513404400, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (34548949440).

21513404400 is an abundant number, since it is smaller than the sum of its proper divisors (47584494480).

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

21513404400 is a wasteful number, since it uses less digits than its factorization.

21513404400 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 47703 (or 47692 counting only the distinct ones).

The product of its (nonzero) digits is 1920, while the sum is 24.

Adding to 21513404400 its reverse (440431512), we get a palindrome (21953835912).

The spelling of 21513404400 in words is "twenty-one billion, five hundred thirteen million, four hundred four thousand, four hundred".