21204043400 has 96 divisors (see below), whose sum is σ = 50946382080. Its totient is φ = 8198880000.

The previous prime is 21204043387. The next prime is 21204043411. The reversal of 21204043400 is 434040212.

It is a super-2 number, since 2×21204043400² (a number of 21 digits) contains 22 as substring.

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

It is an unprimeable number.

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, 8995022 + ... + 8997378.

It is an arithmetic number, because the mean of its divisors is an integer number (530691480).

Almost surely, 2^21204043400 is an apocalyptic number.

21204043400 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 21204043400, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (25473191040).

21204043400 is an abundant number, since it is smaller than the sum of its proper divisors (29742338680).

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

21204043400 is a wasteful number, since it uses less digits than its factorization.

21204043400 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 3855 (or 3846 counting only the distinct ones).

The product of its (nonzero) digits is 768, while the sum is 20.

Adding to 21204043400 its reverse (434040212), we get a palindrome (21638083612).

The spelling of 21204043400 in words is "twenty-one billion, two hundred four million, forty-three thousand, four hundred".