21402224 has 20 divisors (see below), whose sum is σ = 41571744. Its totient is φ = 10674048.

The previous prime is 21402223. The next prime is 21402229. The reversal of 21402224 is 42220412.

It is a happy number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21402221) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 5849 + ... + 8775.

Almost surely, 2^21402224 is an apocalyptic number.

It is an amenable number.

21402224 is a deficient number, since it is larger than the sum of its proper divisors (20169520).

21402224 is a wasteful number, since it uses less digits than its factorization.

21402224 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 3392 (or 3386 counting only the distinct ones).

The product of its (nonzero) digits is 256, while the sum is 17.

The square root of 21402224 is about 4626.2537760049. The cubic root of 21402224 is about 277.6427272167.

Adding to 21402224 its reverse (42220412), we get a palindrome (63622636).

The spelling of 21402224 in words is "twenty-one million, four hundred two thousand, two hundred twenty-four".