1665836385661 has 16 divisors (see below), whose sum is σ = 1923779933568. Its totient is φ = 1412901000000.

The previous prime is 1665836385641. The next prime is 1665836385671.

1665836385661 is nontrivially palindromic in base 10.

It is not a de Polignac number, because 1665836385661 - 2¹¹ = 1665836383613 is a prime.

It is a Duffinian number.

It is a junction number, because it is equal to n+sod(n) for n = 1665836385593 and 1665836385602.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (1665836385601) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 534411 + ... + 1901911.

It is an arithmetic number, because the mean of its divisors is an integer number (120236245848).

Almost surely, 2^{1665836385661} is an apocalyptic number.

It is an amenable number.

1665836385661 is a deficient number, since it is larger than the sum of its proper divisors (257943547907).

1665836385661 is a wasteful number, since it uses less digits than its factorization.

1665836385661 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1369332.

The product of its digits is 111974400, while the sum is 64.

The spelling of 1665836385661 in words is "one trillion, six hundred sixty-five billion, eight hundred thirty-six million, three hundred eighty-five thousand, six hundred sixty-one".