22515221 has 4 divisors (see below), whose sum is σ = 22541772. Its totient is φ = 22488672.

The previous prime is 22515217. The next prime is 22515239. The reversal of 22515221 is 12251522.

It is a happy number.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 12251522 = 2 ⋅6125761.

It can be written as a sum of positive squares in 2 ways, for example, as 19018321 + 3496900 = 4361^2 + 1870^2 .

It is a cyclic number.

It is not a de Polignac number, because 22515221 - 2² = 22515217 is a prime.

It is a Duffinian number.

It is a junction number, because it is equal to n+sod(n) for n = 22515193 and 22515202.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (22515211) by changing a digit.

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, 11960 + ... + 13713.

It is an arithmetic number, because the mean of its divisors is an integer number (5635443).

Almost surely, 2^22515221 is an apocalyptic number.

It is an amenable number.

22515221 is a deficient number, since it is larger than the sum of its proper divisors (26551).

22515221 is an equidigital number, since it uses as much as digits as its factorization.

22515221 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 26550.

The product of its digits is 400, while the sum is 20.

The square root of 22515221 is about 4745.0206532743. The cubic root of 22515221 is about 282.3744543564.

Adding to 22515221 its reverse (12251522), we get a palindrome (34766743).

The spelling of 22515221 in words is "twenty-two million, five hundred fifteen thousand, two hundred twenty-one".