21424430 has 16 divisors (see below), whose sum is σ = 38797920. Its totient is φ = 8517792.

The previous prime is 21424421. The next prime is 21424439. The reversal of 21424430 is 3442412.

It is an interprime number because it is at equal distance from previous prime (21424421) and next prime (21424439).

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21424439) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 4745 + ... + 8084.

It is an arithmetic number, because the mean of its divisors is an integer number (2424870).

Almost surely, 2^21424430 is an apocalyptic number.

21424430 is a deficient number, since it is larger than the sum of its proper divisors (17373490).

21424430 is a wasteful number, since it uses less digits than its factorization.

21424430 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 13003.

The product of its (nonzero) digits is 768, while the sum is 20.

The square root of 21424430 is about 4628.6531518359. The cubic root of 21424430 is about 277.7387172928.

Adding to 21424430 its reverse (3442412), we get a palindrome (24866842).

The spelling of 21424430 in words is "twenty-one million, four hundred twenty-four thousand, four hundred thirty".