21228415 has 16 divisors (see below), whose sum is σ = 28879200. Its totient is φ = 14850432.

The previous prime is 21228409. The next prime is 21228421. The reversal of 21228415 is 51482212.

It is an interprime number because it is at equal distance from previous prime (21228409) and next prime (21228421).

It is a cyclic number.

It is not a de Polignac number, because 21228415 - 2¹¹ = 21226367 is a prime.

It is a self number, because there is not a number n which added to its sum of digits gives 21228415.

It is a congruent number.

It is an unprimeable number.

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 15 ways as a sum of consecutive naturals, for example, 7360 + ... + 9829.

It is an arithmetic number, because the mean of its divisors is an integer number (1804950).

Almost surely, 2^21228415 is an apocalyptic number.

21228415 is a deficient number, since it is larger than the sum of its proper divisors (7650785).

21228415 is a wasteful number, since it uses less digits than its factorization.

21228415 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 17226.

The product of its digits is 1280, while the sum is 25.

The square root of 21228415 is about 4607.4304118456. The cubic root of 21228415 is about 276.8890979103.

The spelling of 21228415 in words is "twenty-one million, two hundred twenty-eight thousand, four hundred fifteen".