21224663 has 4 divisors (see below), whose sum is σ = 21243648. Its totient is φ = 21205680.

The previous prime is 21224659. The next prime is 21224689. The reversal of 21224663 is 36642212.

It is a semiprime because it is the product of two primes.

It is a cyclic number.

It is not a de Polignac number, because 21224663 - 2² = 21224659 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21224633) 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, 7703 + ... + 10088.

It is an arithmetic number, because the mean of its divisors is an integer number (5310912).

Almost surely, 2^21224663 is an apocalyptic number.

21224663 is a deficient number, since it is larger than the sum of its proper divisors (18985).

21224663 is a wasteful number, since it uses less digits than its factorization.

21224663 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 18984.

The product of its digits is 3456, while the sum is 26.

The square root of 21224663 is about 4607.0232254678. The cubic root of 21224663 is about 276.8727840984.

Adding to 21224663 its reverse (36642212), we get a palindrome (57866875).

The spelling of 21224663 in words is "twenty-one million, two hundred twenty-four thousand, six hundred sixty-three".