1666978923 has 8 divisors (see below), whose sum is σ = 2223281808. Its totient is φ = 1110997664.

The previous prime is 1666978913. The next prime is 1666978931. The reversal of 1666978923 is 3298796661.

It is a happy number.

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 1666978923 - 2¹⁷ = 1666847851 is a prime.

It is not an unprimeable number, because it can be changed into a prime (1666978913) 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, 68040 + ... + 89237.

It is an arithmetic number, because the mean of its divisors is an integer number (277910226).

Almost surely, 2^1666978923 is an apocalyptic number.

1666978923 is a deficient number, since it is larger than the sum of its proper divisors (556302885).

1666978923 is a wasteful number, since it uses less digits than its factorization.

1666978923 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 160813.

The product of its digits is 5878656, while the sum is 57.

The square root of 1666978923 is about 40828.6532107049. The cubic root of 1666978923 is about 1185.7051410371.

The spelling of 1666978923 in words is "one billion, six hundred sixty-six million, nine hundred seventy-eight thousand, nine hundred twenty-three".