21533322400 has 72 divisors (see below), whose sum is σ = 52606437660. Its totient is φ = 8607068160.

The previous prime is 21533322373. The next prime is 21533322409. The reversal of 21533322400 is 422333512.

It can be written as a sum of positive squares in 6 ways, for example, as 11126874256 + 10406448144 = 105484^2 + 102012^2 .

It is a Harshad number since it is a multiple of its sum of digits (25).

It is not an unprimeable number, because it can be changed into a prime (21533322409) by changing a digit.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 1182162 + ... + 1200238.

Almost surely, 2^21533322400 is an apocalyptic number.

21533322400 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 21533322400, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (26303218830).

21533322400 is an abundant number, since it is smaller than the sum of its proper divisors (31073115260).

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

21533322400 is a wasteful number, since it uses less digits than its factorization.

21533322400 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 19586 (or 19573 counting only the distinct ones).

The product of its (nonzero) digits is 4320, while the sum is 25.

Adding to 21533322400 its reverse (422333512), we get a palindrome (21955655912).

The spelling of 21533322400 in words is "twenty-one billion, five hundred thirty-three million, three hundred twenty-two thousand, four hundred".