561165221 has 4 divisors (see below), whose sum is σ = 561966444. Its totient is φ = 560364000.

The previous prime is 561165217. The next prime is 561165233. The reversal of 561165221 is 122561165.

It is a happy number.

561165221 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.

It can be written as a sum of positive squares in 2 ways, for example, as 308704900 + 252460321 = 17570^2 + 15889^2 .

It is a cyclic number.

It is not a de Polignac number, because 561165221 - 2² = 561165217 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 (561165251) 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, 399560 + ... + 400961.

It is an arithmetic number, because the mean of its divisors is an integer number (140491611).

Almost surely, 2^561165221 is an apocalyptic number.

It is an amenable number.

561165221 is a deficient number, since it is larger than the sum of its proper divisors (801223).

561165221 is an equidigital number, since it uses as much as digits as its factorization.

561165221 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 801222.

The product of its digits is 3600, while the sum is 29.

The square root of 561165221 is about 23688.9261259349. The cubic root of 561165221 is about 824.8283553532.

The spelling of 561165221 in words is "five hundred sixty-one million, one hundred sixty-five thousand, two hundred twenty-one".