561695209 has 2 divisors, whose sum is σ = 561695210. Its totient is φ = 561695208.

The previous prime is 561695207. The next prime is 561695221. The reversal of 561695209 is 902596165.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 557904400 + 3790809 = 23620^2 + 1947^2 .

It is a cyclic number.

It is not a de Polignac number, because 561695209 - 2¹ = 561695207 is a prime.

Together with 561695207, it forms a pair of twin primes.

It is not a weakly prime, because it can be changed into another prime (561695207) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 280847604 + 280847605.

It is an arithmetic number, because the mean of its divisors is an integer number (280847605).

Almost surely, 2^561695209 is an apocalyptic number.

It is an amenable number.

561695209 is a deficient number, since it is larger than the sum of its proper divisors (1).

561695209 is an equidigital number, since it uses as much as digits as its factorization.

561695209 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 145800, while the sum is 43.

The square root of 561695209 is about 23700.1098942600. The cubic root of 561695209 is about 825.0879411612.

The spelling of 561695209 in words is "five hundred sixty-one million, six hundred ninety-five thousand, two hundred nine".