665718749 has 2 divisors, whose sum is σ = 665718750. Its totient is φ = 665718748.

The previous prime is 665718737. The next prime is 665718829. The reversal of 665718749 is 947817566.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 407313124 + 258405625 = 20182^2 + 16075^2 .

It is a cyclic number.

It is not a de Polignac number, because 665718749 - 2¹⁶ = 665653213 is a prime.

It is a self number, because there is not a number n which added to its sum of digits gives 665718749.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (665718709) 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, 332859374 + 332859375.

It is an arithmetic number, because the mean of its divisors is an integer number (332859375).

Almost surely, 2^665718749 is an apocalyptic number.

It is an amenable number.

665718749 is a deficient number, since it is larger than the sum of its proper divisors (1).

665718749 is an equidigital number, since it uses as much as digits as its factorization.

665718749 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 2540160, while the sum is 53.

The square root of 665718749 is about 25801.5260982757. The cubic root of 665718749 is about 873.1662271648.

The spelling of 665718749 in words is "six hundred sixty-five million, seven hundred eighteen thousand, seven hundred forty-nine".