1666391289 has 8 divisors (see below), whose sum is σ = 2352552480. Its totient is φ = 1045578816.

The previous prime is 1666391273. The next prime is 1666391299. The reversal of 1666391289 is 9821936661.

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

It is not a de Polignac number, because 1666391289 - 2⁴ = 1666391273 is a prime.

It is a Harshad number since it is a multiple of its sum of digits (51), and also a Moran number because the ratio is a prime number: 32674339 = 1666391289 / (1 + 6 + 6 + 6 + 3 + 9 + 1 + 2 + 8 + 9).

It is not an unprimeable number, because it can be changed into a prime (1666391299) 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 7 ways as a sum of consecutive naturals, for example, 16337119 + ... + 16337220.

It is an arithmetic number, because the mean of its divisors is an integer number (294069060).

Almost surely, 2^1666391289 is an apocalyptic number.

It is an amenable number.

1666391289 is a deficient number, since it is larger than the sum of its proper divisors (686161191).

1666391289 is a wasteful number, since it uses less digits than its factorization.

1666391289 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 32674359.

The product of its digits is 839808, while the sum is 51.

The square root of 1666391289 is about 40821.4562332115. The cubic root of 1666391289 is about 1185.5657986347.

The spelling of 1666391289 in words is "one billion, six hundred sixty-six million, three hundred ninety-one thousand, two hundred eighty-nine".