21222455 has 4 divisors (see below), whose sum is σ = 25466952. Its totient is φ = 16977960.

The previous prime is 21222433. The next prime is 21222469. The reversal of 21222455 is 55422212.

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

It is not a de Polignac number, because 21222455 - 2⁶ = 21222391 is a prime.

It is a Duffinian number.

It is a self number, because there is not a number n which added to its sum of digits gives 21222455.

It is a congruent 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, 2122241 + ... + 2122250.

It is an arithmetic number, because the mean of its divisors is an integer number (6366738).

Almost surely, 2^21222455 is an apocalyptic number.

21222455 is a deficient number, since it is larger than the sum of its proper divisors (4244497).

21222455 is an equidigital number, since it uses as much as digits as its factorization.

21222455 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 4244496.

The product of its digits is 1600, while the sum is 23.

The square root of 21222455 is about 4606.7835851058. The cubic root of 21222455 is about 276.8631827475.

Adding to 21222455 its reverse (55422212), we get a palindrome (76644667).

The spelling of 21222455 in words is "twenty-one million, two hundred twenty-two thousand, four hundred fifty-five".