665618399 has 2 divisors, whose sum is σ = 665618400. Its totient is φ = 665618398.

The previous prime is 665618347. The next prime is 665618441. The reversal of 665618399 is 993816566.

It is a strong prime.

It is a cyclic number.

It is not a de Polignac number, because 665618399 - 2¹² = 665614303 is a prime.

It is a self number, because there is not a number n which added to its sum of digits gives 665618399.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (665618339) 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, 332809199 + 332809200.

It is an arithmetic number, because the mean of its divisors is an integer number (332809200).

Almost surely, 2^665618399 is an apocalyptic number.

665618399 is a deficient number, since it is larger than the sum of its proper divisors (1).

665618399 is an equidigital number, since it uses as much as digits as its factorization.

665618399 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 2099520, while the sum is 53.

The square root of 665618399 is about 25799.5813725727. The cubic root of 665618399 is about 873.1223514620.

The spelling of 665618399 in words is "six hundred sixty-five million, six hundred eighteen thousand, three hundred ninety-nine".