665719979 has 2 divisors, whose sum is σ = 665719980. Its totient is φ = 665719978.

The previous prime is 665719963. The next prime is 665720047. The reversal of 665719979 is 979917566.

It is a weak prime.

It is a cyclic number.

It is not a de Polignac number, because 665719979 - 2⁴ = 665719963 is a prime.

It is not a weakly prime, because it can be changed into another prime (665719919) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 332859989 + 332859990.

It is an arithmetic number, because the mean of its divisors is an integer number (332859990).

Almost surely, 2^665719979 is an apocalyptic number.

665719979 is a deficient number, since it is larger than the sum of its proper divisors (1).

665719979 is an equidigital number, since it uses as much as digits as its factorization.

665719979 is an evil number, because the sum of its binary digits is even.

The product of its digits is 6429780, while the sum is 59.

The square root of 665719979 is about 25801.5499340640. The cubic root of 665719979 is about 873.1667649263.

The spelling of 665719979 in words is "six hundred sixty-five million, seven hundred nineteen thousand, nine hundred seventy-nine".