665640719 has 2 divisors, whose sum is σ = 665640720. Its totient is φ = 665640718.

The previous prime is 665640707. The next prime is 665640751. The reversal of 665640719 is 917046566.

It is a happy number.

It is a weak prime.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-665640719 is a prime.

It is a super-2 number, since 2×665640719² = 886155133581673922, which contains 22 as substring.

It is a self number, because there is not a number n which added to its sum of digits gives 665640719.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (665640919) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (19) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 332820359 + 332820360.

It is an arithmetic number, because the mean of its divisors is an integer number (332820360).

Almost surely, 2^665640719 is an apocalyptic number.

665640719 is a deficient number, since it is larger than the sum of its proper divisors (1).

665640719 is an equidigital number, since it uses as much as digits as its factorization.

665640719 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 272160, while the sum is 44.

The square root of 665640719 is about 25800.0139341048. The cubic root of 665640719 is about 873.1321107440.

The spelling of 665640719 in words is "six hundred sixty-five million, six hundred forty thousand, seven hundred nineteen".