21430400 has 96 divisors (see below), whose sum is σ = 54670980. Its totient is φ = 8294400.

The previous prime is 21430379. The next prime is 21430403. The reversal of 21430400 is 403412.

It can be written as a sum of positive squares in 6 ways, for example, as 5494336 + 15936064 = 2344^2 + 3992^2 .

It is not an unprimeable number, because it can be changed into a prime (21430403) 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, 118310 + ... + 118490.

Almost surely, 2^21430400 is an apocalyptic number.

21430400 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 21430400, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (27335490).

21430400 is an abundant number, since it is smaller than the sum of its proper divisors (33240580).

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

21430400 is a wasteful number, since it uses less digits than its factorization.

21430400 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 242 (or 225 counting only the distinct ones).

The product of its (nonzero) digits is 96, while the sum is 14.

The square root of 21430400 is about 4629.2980029374. The cubic root of 21430400 is about 277.7645125517.

Adding to 21430400 its reverse (403412), we get a palindrome (21833812).

The spelling of 21430400 in words is "twenty-one million, four hundred thirty thousand, four hundred".