21424456 has 16 divisors (see below), whose sum is σ = 40771440. Its totient is φ = 10552080.

The previous prime is 21424451. The next prime is 21424489. The reversal of 21424456 is 65442412.

It is not an unprimeable number, because it can be changed into a prime (21424451) 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 3 ways as a sum of consecutive naturals, for example, 19450 + ... + 20521.

It is an arithmetic number, because the mean of its divisors is an integer number (2548215).

Almost surely, 2^21424456 is an apocalyptic number.

It is an amenable number.

21424456 is a deficient number, since it is larger than the sum of its proper divisors (19346984).

21424456 is a wasteful number, since it uses less digits than its factorization.

21424456 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 40044 (or 40040 counting only the distinct ones).

The product of its digits is 7680, while the sum is 28.

The square root of 21424456 is about 4628.6559604274. The cubic root of 21424456 is about 277.7388296444.

Adding to 21424456 its reverse (65442412), we get a palindrome (86866868).

The spelling of 21424456 in words is "twenty-one million, four hundred twenty-four thousand, four hundred fifty-six".