21530430400 has 84 divisors (see below), whose sum is σ = 53524869328. Its totient is φ = 8523325440.

The previous prime is 21530430379. The next prime is 21530430401. The reversal of 21530430400 is 403403512.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21530430401) 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, 85837 + ... + 224563.

Almost surely, 2^21530430400 is an apocalyptic number.

21530430400 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 21530430400, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (26762434664).

21530430400 is an abundant number, since it is smaller than the sum of its proper divisors (31994438928).

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

21530430400 is a wasteful number, since it uses less digits than its factorization.

21530430400 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 138846 (or 138831 counting only the distinct ones).

The product of its (nonzero) digits is 1440, while the sum is 22.

Adding to 21530430400 its reverse (403403512), we get a palindrome (21933833912).

The spelling of 21530430400 in words is "twenty-one billion, five hundred thirty million, four hundred thirty thousand, four hundred".