665967749 has 2 divisors, whose sum is σ = 665967750. Its totient is φ = 665967748.

The previous prime is 665967721. The next prime is 665967767. The reversal of 665967749 is 947769566.

It is a happy number.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 665278849 + 688900 = 25793^2 + 830^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-665967749 is a prime.

It is a Chen prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (665967779) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 332983874 + 332983875.

It is an arithmetic number, because the mean of its divisors is an integer number (332983875).

Almost surely, 2^665967749 is an apocalyptic number.

It is an amenable number.

665967749 is a deficient number, since it is larger than the sum of its proper divisors (1).

665967749 is an equidigital number, since it uses as much as digits as its factorization.

665967749 is an evil number, because the sum of its binary digits is even.

The product of its digits is 17146080, while the sum is 59.

The square root of 665967749 is about 25806.3509431303. The cubic root of 665967749 is about 873.2750775812.

The spelling of 665967749 in words is "six hundred sixty-five million, nine hundred sixty-seven thousand, seven hundred forty-nine".