561666055663 has 2 divisors, whose sum is σ = 561666055664. Its totient is φ = 561666055662.

The previous prime is 561666055543. The next prime is 561666055721. The reversal of 561666055663 is 366550666165.

It is a happy number.

It is a strong prime.

It is a cyclic number.

It is not a de Polignac number, because 561666055663 - 2¹⁷ = 561665924591 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (561666055063) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 280833027831 + 280833027832.

It is an arithmetic number, because the mean of its divisors is an integer number (280833027832).

Almost surely, 2^561666055663 is an apocalyptic number.

561666055663 is a deficient number, since it is larger than the sum of its proper divisors (1).

561666055663 is an equidigital number, since it uses as much as digits as its factorization.

561666055663 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 17496000, while the sum is 55.

The spelling of 561666055663 in words is "five hundred sixty-one billion, six hundred sixty-six million, fifty-five thousand, six hundred sixty-three".