521605465561 has 2 divisors, whose sum is σ = 521605465562. Its totient is φ = 521605465560.

The previous prime is 521605465543. The next prime is 521605465571. The reversal of 521605465561 is 165564506125.

It is a happy number.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 423109919961 + 98495545600 = 650469^2 + 313840^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-521605465561 is a prime.

It is not a weakly prime, because it can be changed into another prime (521605465571) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 260802732780 + 260802732781.

It is an arithmetic number, because the mean of its divisors is an integer number (260802732781).

Almost surely, 2^521605465561 is an apocalyptic number.

It is an amenable number.

521605465561 is a deficient number, since it is larger than the sum of its proper divisors (1).

521605465561 is an equidigital number, since it uses as much as digits as its factorization.

521605465561 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 1080000, while the sum is 46.

The spelling of 521605465561 in words is "five hundred twenty-one billion, six hundred five million, four hundred sixty-five thousand, five hundred sixty-one".