21424736 has 24 divisors (see below), whose sum is σ = 43636320. Its totient is φ = 10342528.

The previous prime is 21424699. The next prime is 21424759. The reversal of 21424736 is 63742412.

It is a Harshad number since it is a multiple of its sum of digits (29).

It is a junction number, because it is equal to n+sod(n) for n = 21424699 and 21424708.

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 3 ways as a sum of consecutive naturals, for example, 10616 + ... + 12471.

It is an arithmetic number, because the mean of its divisors is an integer number (1818180).

Almost surely, 2^21424736 is an apocalyptic number.

It is an amenable number.

21424736 is an abundant number, since it is smaller than the sum of its proper divisors (22211584).

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

21424736 is a wasteful number, since it uses less digits than its factorization.

21424736 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 23126 (or 23118 counting only the distinct ones).

The product of its digits is 8064, while the sum is 29.

The square root of 21424736 is about 4628.6862066898. The cubic root of 21424736 is about 277.7400395784.

The spelling of 21424736 in words is "twenty-one million, four hundred twenty-four thousand, seven hundred thirty-six".