1666768979 has 4 divisors (see below), whose sum is σ = 1670369376. Its totient is φ = 1663168584.

The previous prime is 1666768951. The next prime is 1666769009. The reversal of 1666768979 is 9798676661.

It is a happy number.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 9798676661 = 8243 ⋅1188727.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-1666768979 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (1666768919) 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, 1799504 + ... + 1800429.

It is an arithmetic number, because the mean of its divisors is an integer number (417592344).

Almost surely, 2^1666768979 is an apocalyptic number.

1666768979 is a deficient number, since it is larger than the sum of its proper divisors (3600397).

1666768979 is an equidigital number, since it uses as much as digits as its factorization.

1666768979 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 3600396.

The product of its digits is 41150592, while the sum is 65.

The square root of 1666768979 is about 40826.0820922116. The cubic root of 1666768979 is about 1185.6553619372.

The spelling of 1666768979 in words is "one billion, six hundred sixty-six million, seven hundred sixty-eight thousand, nine hundred seventy-nine".