21135430400 has 216 divisors, whose sum is σ = 59961099744. Its totient is φ = 7225344000.

The previous prime is 21135430397. The next prime is 21135430403. The reversal of 21135430400 is 403453112.

It is an interprime number because it is at equal distance from previous prime (21135430397) and next prime (21135430403).

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21135430403) by changing a digit.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 30150050 + ... + 30150750.

It is an arithmetic number, because the mean of its divisors is an integer number (277597684).

Almost surely, 2^21135430400 is an apocalyptic number.

21135430400 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 21135430400, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (29980549872).

21135430400 is an abundant number, since it is smaller than the sum of its proper divisors (38825669344).

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

21135430400 is an equidigital number, since it uses as much as digits as its factorization.

21135430400 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1407 (or 1388 counting only the distinct ones).

The product of its (nonzero) digits is 1440, while the sum is 23.

Adding to 21135430400 its reverse (403453112), we get a palindrome (21538883512).

The spelling of 21135430400 in words is "twenty-one billion, one hundred thirty-five million, four hundred thirty thousand, four hundred".