1561661112065 has 4 divisors (see below), whose sum is σ = 1873993334484. Its totient is φ = 1249328889648.

The previous prime is 1561661112059. The next prime is 1561661112163. The reversal of 1561661112065 is 5602111661651.

It is a happy number.

It is a semiprime because it is the product of two primes.

It can be written as a sum of positive squares in 2 ways, for example, as 158364998401 + 1403296113664 = 397951^2 + 1184608^2 .

It is a cyclic number.

It is not a de Polignac number, because 1561661112065 - 2⁸ = 1561661111809 is a prime.

It is a Duffinian number.

It is an unprimeable number.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 156166111202 + ... + 156166111211.

It is an arithmetic number, because the mean of its divisors is an integer number (468498333621).

Almost surely, 2^{1561661112065} is an apocalyptic number.

It is an amenable number.

1561661112065 is a deficient number, since it is larger than the sum of its proper divisors (312332222419).

1561661112065 is an equidigital number, since it uses as much as digits as its factorization.

1561661112065 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 312332222418.

The product of its (nonzero) digits is 64800, while the sum is 41.

The spelling of 1561661112065 in words is "one trillion, five hundred sixty-one billion, six hundred sixty-one million, one hundred twelve thousand, sixty-five".