15665616445961 has 2 divisors, whose sum is σ = 15665616445962. Its totient is φ = 15665616445960.

The previous prime is 15665616445957. The next prime is 15665616446009. The reversal of 15665616445961 is 16954461656651.

15665616445961 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 14662343772736 + 1003272673225 = 3829144^2 + 1001635^2 .

It is a cyclic number.

It is not a de Polignac number, because 15665616445961 - 2² = 15665616445957 is a prime.

It is not a weakly prime, because it can be changed into another prime (15665616445901) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 7832808222980 + 7832808222981.

It is an arithmetic number, because the mean of its divisors is an integer number (7832808222981).

Almost surely, 2^{15665616445961} is an apocalyptic number.

It is an amenable number.

15665616445961 is a deficient number, since it is larger than the sum of its proper divisors (1).

15665616445961 is an equidigital number, since it uses as much as digits as its factorization.

15665616445961 is an evil number, because the sum of its binary digits is even.

The product of its digits is 139968000, while the sum is 65.

The spelling of 15665616445961 in words is "fifteen trillion, six hundred sixty-five billion, six hundred sixteen million, four hundred forty-five thousand, nine hundred sixty-one".