1666078865 has 16 divisors (see below), whose sum is σ = 2181854016. Its totient is φ = 1211246400.

The previous prime is 1666078861. The next prime is 1666078871. The reversal of 1666078865 is 5688706661.

It is not a de Polignac number, because 1666078865 - 2² = 1666078861 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (1666078861) 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, 249875 + ... + 256455.

It is an arithmetic number, because the mean of its divisors is an integer number (136365876).

Almost surely, 2^1666078865 is an apocalyptic number.

It is an amenable number.

1666078865 is a deficient number, since it is larger than the sum of its proper divisors (515775151).

1666078865 is a wasteful number, since it uses less digits than its factorization.

1666078865 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 11200.

The product of its (nonzero) digits is 2903040, while the sum is 53.

The square root of 1666078865 is about 40817.6293407640. The cubic root of 1666078865 is about 1185.4917019200.

The spelling of 1666078865 in words is "one billion, six hundred sixty-six million, seventy-eight thousand, eight hundred sixty-five".