21253430 has 32 divisors (see below), whose sum is σ = 42169248. Its totient is φ = 7648000.

The previous prime is 21253423. The next prime is 21253459. The reversal of 21253430 is 3435212.

It is a happy number.

It is a congruent number.

It is an unprimeable number.

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 15 ways as a sum of consecutive naturals, for example, 10154 + ... + 12066.

It is an arithmetic number, because the mean of its divisors is an integer number (1317789).

Almost surely, 2^21253430 is an apocalyptic number.

21253430 is a deficient number, since it is larger than the sum of its proper divisors (20915818).

21253430 is a wasteful number, since it uses less digits than its factorization.

21253430 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 2032.

The product of its (nonzero) digits is 720, while the sum is 20.

The square root of 21253430 is about 4610.1442493701. The cubic root of 21253430 is about 276.9978148029.

Adding to 21253430 its reverse (3435212), we get a palindrome (24688642).

It can be divided in two parts, 2125 and 3430, that added together give a palindrome (5555).

The spelling of 21253430 in words is "twenty-one million, two hundred fifty-three thousand, four hundred thirty".