1665440445661 has 8 divisors (see below), whose sum is σ = 1675849280864. Its totient is φ = 1655033945040.

The previous prime is 1665440445637. The next prime is 1665440445671.

1665440445661 is nontrivially palindromic in base 10.

It is a sphenic number, since it is the product of 3 distinct primes.

It is a cyclic number.

It is not a de Polignac number, because 1665440445661 - 2¹⁵ = 1665440412893 is a prime.

It is a Duffinian number.

It is a junction number, because it is equal to n+sod(n) for n = 1665440445599 and 1665440445608.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (1665440445601) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 858670 + ... + 2016976.

It is an arithmetic number, because the mean of its divisors is an integer number (209481160108).

Almost surely, 2^{1665440445661} is an apocalyptic number.

It is an amenable number.

1665440445661 is a deficient number, since it is larger than the sum of its proper divisors (10408835203).

1665440445661 is a wasteful number, since it uses less digits than its factorization.

1665440445661 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1167291.

The product of its (nonzero) digits is 8294400, while the sum is 52.

The spelling of 1665440445661 in words is "one trillion, six hundred sixty-five billion, four hundred forty million, four hundred forty-five thousand, six hundred sixty-one".