561090721 has 2 divisors, whose sum is σ = 561090722. Its totient is φ = 561090720.

The previous prime is 561090713. The next prime is 561090743. The reversal of 561090721 is 127090165.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 292786321 + 268304400 = 17111^2 + 16380^2 .

It is a cyclic number.

It is not a de Polignac number, because 561090721 - 2³ = 561090713 is a prime.

It is a Chen prime.

It is an alternating number because its digits alternate between odd and even.

It is not a weakly prime, because it can be changed into another prime (561090791) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 280545360 + 280545361.

It is an arithmetic number, because the mean of its divisors is an integer number (280545361).

Almost surely, 2^561090721 is an apocalyptic number.

It is an amenable number.

561090721 is a deficient number, since it is larger than the sum of its proper divisors (1).

561090721 is an equidigital number, since it uses as much as digits as its factorization.

561090721 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 3780, while the sum is 31.

The square root of 561090721 is about 23687.3536090463. The cubic root of 561090721 is about 824.7918524781.

The spelling of 561090721 in words is "five hundred sixty-one million, ninety thousand, seven hundred twenty-one".