1668727979 has 4 divisors (see below), whose sum is σ = 1684037520. Its totient is φ = 1653418440.

The previous prime is 1668727967. The next prime is 1668727999. The reversal of 1668727979 is 9797278661.

It is a semiprime because it is the product of two primes.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-1668727979 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (1668727999) 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 3 ways as a sum of consecutive naturals, for example, 7654607 + ... + 7654824.

It is an arithmetic number, because the mean of its divisors is an integer number (421009380).

Almost surely, 2^1668727979 is an apocalyptic number.

1668727979 is a deficient number, since it is larger than the sum of its proper divisors (15309541).

1668727979 is a wasteful number, since it uses less digits than its factorization.

1668727979 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 15309540.

The product of its digits is 16003008, while the sum is 62.

The square root of 1668727979 is about 40850.0670623685. The cubic root of 1668727979 is about 1186.1196913272.

The spelling of 1668727979 in words is "one billion, six hundred sixty-eight million, seven hundred twenty-seven thousand, nine hundred seventy-nine".