21222115 has 4 divisors (see below), whose sum is σ = 25466544. Its totient is φ = 16977688.

The previous prime is 21222043. The next prime is 21222143. The reversal of 21222115 is 51122212.

It is a happy number.

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 21222115 - 2¹³ = 21213923 is a prime.

It is a Duffinian number.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 2122207 + ... + 2122216.

It is an arithmetic number, because the mean of its divisors is an integer number (6366636).

Almost surely, 2^21222115 is an apocalyptic number.

21222115 is a deficient number, since it is larger than the sum of its proper divisors (4244429).

21222115 is an equidigital number, since it uses as much as digits as its factorization.

21222115 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 4244428.

The product of its digits is 80, while the sum is 16.

The square root of 21222115 is about 4606.7466828555. The cubic root of 21222115 is about 276.8617042195.

Adding to 21222115 its reverse (51122212), we get a palindrome (72344327).

The spelling of 21222115 in words is "twenty-one million, two hundred twenty-two thousand, one hundred fifteen".