21211045 has 4 divisors (see below), whose sum is σ = 25453260. Its totient is φ = 16968832.

The previous prime is 21211039. The next prime is 21211079. The reversal of 21211045 is 54011212.

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

It can be written as a sum of positive squares in 2 ways, for example, as 3621409 + 17589636 = 1903^2 + 4194^2 .

It is a cyclic number.

It is not a de Polignac number, because 21211045 - 2⁵ = 21211013 is a prime.

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, 2121100 + ... + 2121109.

It is an arithmetic number, because the mean of its divisors is an integer number (6363315).

Almost surely, 2^21211045 is an apocalyptic number.

It is an amenable number.

21211045 is a deficient number, since it is larger than the sum of its proper divisors (4242215).

21211045 is an equidigital number, since it uses as much as digits as its factorization.

21211045 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 4242214.

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

The square root of 21211045 is about 4605.5450274642. The cubic root of 21211045 is about 276.8135564560.

Adding to 21211045 its reverse (54011212), we get a palindrome (75222257).

The spelling of 21211045 in words is "twenty-one million, two hundred eleven thousand, forty-five".