21423400 has 48 divisors (see below), whose sum is σ = 52747740. Its totient is φ = 8064000.

The previous prime is 21423377. The next prime is 21423403. The reversal of 21423400 is 432412.

It can be written as a sum of positive squares in 6 ways, for example, as 12096484 + 9326916 = 3478^2 + 3054^2 .

It is not an unprimeable number, because it can be changed into a prime (21423403) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 250 + ... + 6550.

Almost surely, 2^21423400 is an apocalyptic number.

21423400 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 21423400, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (26373870).

21423400 is an abundant number, since it is smaller than the sum of its proper divisors (31324340).

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

21423400 is a wasteful number, since it uses less digits than its factorization.

21423400 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 6334 (or 6325 counting only the distinct ones).

The product of its (nonzero) digits is 192, while the sum is 16.

The square root of 21423400 is about 4628.5418870309. The cubic root of 21423400 is about 277.7342663699.

Adding to 21423400 its reverse (432412), we get a palindrome (21855812).

The spelling of 21423400 in words is "twenty-one million, four hundred twenty-three thousand, four hundred".