21228479 has 4 divisors (see below), whose sum is σ = 21426984. Its totient is φ = 21029976.

The previous prime is 21228469. The next prime is 21228509. The reversal of 21228479 is 97482212.

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

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-21228479 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 (21228409) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 99092 + ... + 99305.

It is an arithmetic number, because the mean of its divisors is an integer number (5356746).

Almost surely, 2^21228479 is an apocalyptic number.

21228479 is a deficient number, since it is larger than the sum of its proper divisors (198505).

21228479 is a wasteful number, since it uses less digits than its factorization.

21228479 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 198504.

The product of its digits is 16128, while the sum is 35.

The square root of 21228479 is about 4607.4373571433. The cubic root of 21228479 is about 276.8893761676.

It can be divided in two parts, 2122 and 8479, that added together give a palindrome (10601).

The spelling of 21228479 in words is "twenty-one million, two hundred twenty-eight thousand, four hundred seventy-nine".