561666340432521 has 12 divisors (see below), whose sum is σ = 811521624120948. Its totient is φ = 374340012008064.

The previous prime is 561666340432511. The next prime is 561666340432567. The reversal of 561666340432521 is 125234043666165.

It can be written as a sum of positive squares in 2 ways, for example, as 304824048742521 + 256842291690000 = 17459211^2 + 16026300^2 .

It is not a de Polignac number, because 561666340432521 - 2⁹ = 561666340432009 is a prime.

It is not an unprimeable number, because it can be changed into a prime (561666340432511) by changing a digit.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 8684544780 + ... + 8684609453.

It is an arithmetic number, because the mean of its divisors is an integer number (67626802010079).

Almost surely, 2^{561666340432521} is an apocalyptic number.

It is an amenable number.

561666340432521 is a deficient number, since it is larger than the sum of its proper divisors (249855283688427).

561666340432521 is a wasteful number, since it uses less digits than its factorization.

561666340432521 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 17369157832 (or 17369157829 counting only the distinct ones).

The product of its (nonzero) digits is 18662400, while the sum is 54.

The spelling of 561666340432521 in words is "five hundred sixty-one trillion, six hundred sixty-six billion, three hundred forty million, four hundred thirty-two thousand, five hundred twenty-one".