21124200400 has 60 divisors (see below), whose sum is σ = 51988758444. Its totient is φ = 8243584000.

The previous prime is 21124200367. The next prime is 21124200401. The reversal of 21124200400 is 400242112.

It can be written as a sum of positive squares in 6 ways, for example, as 9392711056 + 11731489344 = 96916^2 + 108312^2 .

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 (21124200401) by changing a digit.

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 11 ways as a sum of consecutive naturals, for example, 627631 + ... + 660430.

Almost surely, 2^21124200400 is an apocalyptic number.

21124200400 is a gapful number since it is divisible by the number (20) formed by its first and last digit.

It is an amenable number.

21124200400 is an abundant number, since it is smaller than the sum of its proper divisors (30864558044).

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

21124200400 is a wasteful number, since it uses less digits than its factorization.

21124200400 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1288120 (or 1288109 counting only the distinct ones).

The product of its (nonzero) digits is 128, while the sum is 16.

Adding to 21124200400 its reverse (400242112), we get a palindrome (21524442512).

The spelling of 21124200400 in words is "twenty-one billion, one hundred twenty-four million, two hundred thousand, four hundred".