666791979 has 16 divisors (see below), whose sum is σ = 1040847360. Its totient is φ = 371730240.

The previous prime is 666791963. The next prime is 666791987. The reversal of 666791979 is 979197666.

It is not a de Polignac number, because 666791979 - 2⁴ = 666791963 is a prime.

It is a super-2 number, since 2×666791979² = 889223086517472882, which contains 22 as substring.

It is not an unprimeable number, because it can be changed into a prime (666791959) 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 15 ways as a sum of consecutive naturals, for example, 386359 + ... + 388080.

It is an arithmetic number, because the mean of its divisors is an integer number (65052960).

Almost surely, 2^666791979 is an apocalyptic number.

666791979 is a deficient number, since it is larger than the sum of its proper divisors (374055381).

666791979 is a wasteful number, since it uses less digits than its factorization.

666791979 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 774490.

The product of its digits is 7715736, while the sum is 60.

The square root of 666791979 is about 25822.3155235932. The cubic root of 666791979 is about 873.6351965104.

The spelling of 666791979 in words is "six hundred sixty-six million, seven hundred ninety-one thousand, nine hundred seventy-nine".