1661419788565 has 16 divisors (see below), whose sum is σ = 2025831225600. Its totient is φ = 1307832357312.

The previous prime is 1661419788551. The next prime is 1661419788569. The reversal of 1661419788565 is 5658879141661.

It is a cyclic number.

It is not a de Polignac number, because 1661419788565 - 2²⁵ = 1661386234133 is a prime.

It is a self number, because there is not a number n which added to its sum of digits gives 1661419788565.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (1661419788569) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 7061955 + ... + 7293424.

It is an arithmetic number, because the mean of its divisors is an integer number (126614451600).

Almost surely, 2^{1661419788565} is an apocalyptic number.

It is an amenable number.

1661419788565 is a deficient number, since it is larger than the sum of its proper divisors (364411437035).

1661419788565 is a wasteful number, since it uses less digits than its factorization.

1661419788565 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 14355756.

The product of its digits is 87091200, while the sum is 67.

The spelling of 1661419788565 in words is "one trillion, six hundred sixty-one billion, four hundred nineteen million, seven hundred eighty-eight thousand, five hundred sixty-five".