20006600561 has 2 divisors, whose sum is σ = 20006600562. Its totient is φ = 20006600560.

The previous prime is 20006600557. The next prime is 20006600567. The reversal of 20006600561 is 16500660002.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 15833440561 + 4173160000 = 125831^2 + 64600^2 .

It is a cyclic number.

It is not a de Polignac number, because 20006600561 - 2² = 20006600557 is a prime.

It is a self number, because there is not a number n which added to its sum of digits gives 20006600561.

It is not a weakly prime, because it can be changed into another prime (20006600567) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10003300280 + 10003300281.

It is an arithmetic number, because the mean of its divisors is an integer number (10003300281).

Almost surely, 2^20006600561 is an apocalyptic number.

It is an amenable number.

20006600561 is a deficient number, since it is larger than the sum of its proper divisors (1).

20006600561 is an equidigital number, since it uses as much as digits as its factorization.

20006600561 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 2160, while the sum is 26.

The spelling of 20006600561 in words is "twenty billion, six million, six hundred thousand, five hundred sixty-one".