21424216 has 32 divisors (see below), whose sum is σ = 46403280. Its totient is φ = 9164800.

The previous prime is 21424213. The next prime is 21424217. The reversal of 21424216 is 61242412.

It is a happy number.

It is a Harshad number since it is a multiple of its sum of digits (22).

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21424213) 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 7 ways as a sum of consecutive naturals, for example, 5665 + ... + 8656.

Almost surely, 2^21424216 is an apocalyptic number.

It is an amenable number.

21424216 is an abundant number, since it is smaller than the sum of its proper divisors (24979064).

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

21424216 is a wasteful number, since it uses less digits than its factorization.

21424216 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 14355 (or 14351 counting only the distinct ones).

The product of its digits is 768, while the sum is 22.

The square root of 21424216 is about 4628.6300349023. The cubic root of 21424216 is about 277.7377925497.

Adding to 21424216 its reverse (61242412), we get a palindrome (82666628).

The spelling of 21424216 in words is "twenty-one million, four hundred twenty-four thousand, two hundred sixteen".