561777221 has 2 divisors, whose sum is σ = 561777222. Its totient is φ = 561777220.

The previous prime is 561777211. The next prime is 561777239. The reversal of 561777221 is 122777165.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 519384100 + 42393121 = 22790^2 + 6511^2 .

It is a cyclic number.

It is not a de Polignac number, because 561777221 - 2²⁶ = 494668357 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (561777211) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 280888610 + 280888611.

It is an arithmetic number, because the mean of its divisors is an integer number (280888611).

Almost surely, 2^561777221 is an apocalyptic number.

It is an amenable number.

561777221 is a deficient number, since it is larger than the sum of its proper divisors (1).

561777221 is an equidigital number, since it uses as much as digits as its factorization.

561777221 is an evil number, because the sum of its binary digits is even.

The product of its digits is 41160, while the sum is 38.

The square root of 561777221 is about 23701.8400340564. The cubic root of 561777221 is about 825.1280956899.

The spelling of 561777221 in words is "five hundred sixty-one million, seven hundred seventy-seven thousand, two hundred twenty-one".