1665575861 has 4 divisors (see below), whose sum is σ = 1665697152. Its totient is φ = 1665454572.

The previous prime is 1665575819. The next prime is 1665575869. The reversal of 1665575861 is 1685755661.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4.

It is a cyclic number.

It is not a de Polignac number, because 1665575861 - 2¹⁰ = 1665574837 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (1665575869) 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 3 ways as a sum of consecutive naturals, for example, 36965 + ... + 68538.

It is an arithmetic number, because the mean of its divisors is an integer number (416424288).

Almost surely, 2^1665575861 is an apocalyptic number.

It is an amenable number.

1665575861 is a deficient number, since it is larger than the sum of its proper divisors (121291).

1665575861 is a wasteful number, since it uses less digits than its factorization.

1665575861 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 121290.

The product of its digits is 1512000, while the sum is 50.

The square root of 1665575861 is about 40811.4672733044. The cubic root of 1665575861 is about 1185.3723864221.

The spelling of 1665575861 in words is "one billion, six hundred sixty-five million, five hundred seventy-five thousand, eight hundred sixty-one".