665370649 has 2 divisors, whose sum is σ = 665370650. Its totient is φ = 665370648.

The previous prime is 665370647. The next prime is 665370659. The reversal of 665370649 is 946073566.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 663320025 + 2050624 = 25755^2 + 1432^2 .

It is a cyclic number.

It is not a de Polignac number, because 665370649 - 2¹ = 665370647 is a prime.

Together with 665370647, it forms a pair of twin primes.

It is a junction number, because it is equal to n+sod(n) for n = 665370599 and 665370608.

It is not a weakly prime, because it can be changed into another prime (665370647) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 332685324 + 332685325.

It is an arithmetic number, because the mean of its divisors is an integer number (332685325).

Almost surely, 2^665370649 is an apocalyptic number.

It is an amenable number.

665370649 is a deficient number, since it is larger than the sum of its proper divisors (1).

665370649 is an equidigital number, since it uses as much as digits as its factorization.

665370649 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 816480, while the sum is 46.

The square root of 665370649 is about 25794.7794912071. The cubic root of 665370649 is about 873.0140096519.

The spelling of 665370649 in words is "six hundred sixty-five million, three hundred seventy thousand, six hundred forty-nine".