22209521 has 4 divisors (see below), whose sum is σ = 22682112. Its totient is φ = 21736932.

The previous prime is 22209511. The next prime is 22209527. The reversal of 22209521 is 12590222.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-22209521 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (22209527) 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, 236225 + ... + 236318.

It is an arithmetic number, because the mean of its divisors is an integer number (5670528).

Almost surely, 2^22209521 is an apocalyptic number.

It is an amenable number.

22209521 is a deficient number, since it is larger than the sum of its proper divisors (472591).

22209521 is an equidigital number, since it uses as much as digits as its factorization.

22209521 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 472590.

The product of its (nonzero) digits is 720, while the sum is 23.

The square root of 22209521 is about 4712.6978473057. The cubic root of 22209521 is about 281.0906484307.

Adding to 22209521 its reverse (12590222), we get a palindrome (34799743).

The spelling of 22209521 in words is "twenty-two million, two hundred nine thousand, five hundred twenty-one".