1666818289 has 4 divisors (see below), whose sum is σ = 1677435124. Its totient is φ = 1656201456.

The previous prime is 1666818281. The next prime is 1666818313. The reversal of 1666818289 is 9828186661.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 9828186661 = 28643 ⋅343127.

It can be written as a sum of positive squares in 2 ways, for example, as 812250000 + 854568289 = 28500^2 + 29233^2 .

It is a cyclic number.

It is not a de Polignac number, because 1666818289 - 2³ = 1666818281 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (1666818281) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 5308182 + ... + 5308495.

It is an arithmetic number, because the mean of its divisors is an integer number (419358781).

Almost surely, 2^1666818289 is an apocalyptic number.

It is an amenable number.

1666818289 is a deficient number, since it is larger than the sum of its proper divisors (10616835).

1666818289 is a wasteful number, since it uses less digits than its factorization.

1666818289 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 10616834.

The product of its digits is 1990656, while the sum is 55.

The square root of 1666818289 is about 40826.6859909055. The cubic root of 1666818289 is about 1185.6670540373.

The spelling of 1666818289 in words is "one billion, six hundred sixty-six million, eight hundred eighteen thousand, two hundred eighty-nine".