21362221 has 4 divisors (see below), whose sum is σ = 21404700. Its totient is φ = 21319744.

The previous prime is 21362219. The next prime is 21362227. The reversal of 21362221 is 12226312.

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 13176900 + 8185321 = 3630^2 + 2861^2 .

It is a cyclic number.

It is not a de Polignac number, because 21362221 - 2¹ = 21362219 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 (21362227) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 20476 + ... + 21493.

It is an arithmetic number, because the mean of its divisors is an integer number (5351175).

Almost surely, 2^21362221 is an apocalyptic number.

It is an amenable number.

21362221 is a deficient number, since it is larger than the sum of its proper divisors (42479).

21362221 is an equidigital number, since it uses as much as digits as its factorization.

21362221 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 42478.

The product of its digits is 288, while the sum is 19.

The square root of 21362221 is about 4621.9282772453. The cubic root of 21362221 is about 277.4696382116.

Adding to 21362221 its reverse (12226312), we get a palindrome (33588533).

The spelling of 21362221 in words is "twenty-one million, three hundred sixty-two thousand, two hundred twenty-one".