222521561 has 4 divisors (see below), whose sum is σ = 222554112. Its totient is φ = 222489012.

The previous prime is 222521557. The next prime is 222521567. The reversal of 222521561 is 165125222.

222521561 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

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, and also an emirpimes, since its reverse is a distinct semiprime: 165125222 = 2 ⋅82562611.

It is a cyclic number.

It is not a de Polignac number, because 222521561 - 2² = 222521557 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 222521561.

It is not an unprimeable number, because it can be changed into a prime (222521567) 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, 1625 + ... + 21158.

It is an arithmetic number, because the mean of its divisors is an integer number (55638528).

Almost surely, 2^222521561 is an apocalyptic number.

It is an amenable number.

222521561 is a deficient number, since it is larger than the sum of its proper divisors (32551).

222521561 is an equidigital number, since it uses as much as digits as its factorization.

222521561 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 32550.

The product of its digits is 2400, while the sum is 26.

The square root of 222521561 is about 14917.1565990305. The cubic root of 222521561 is about 605.9787095818.

Adding to 222521561 its reverse (165125222), we get a palindrome (387646783).

The spelling of 222521561 in words is "two hundred twenty-two million, five hundred twenty-one thousand, five hundred sixty-one".