666502649 has 2 divisors, whose sum is σ = 666502650. Its totient is φ = 666502648.

The previous prime is 666502633. The next prime is 666502651. The reversal of 666502649 is 946205666.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 540097600 + 126405049 = 23240^2 + 11243^2 .

It is a cyclic number.

It is not a de Polignac number, because 666502649 - 2⁴ = 666502633 is a prime.

It is a super-2 number, since 2×666502649² = 888451562248034402, which contains 22 as substring.

It is a Sophie Germain prime.

Together with 666502651, it forms a pair of twin primes.

It is a Chen prime.

It is a Curzon number.

It is not a weakly prime, because it can be changed into another prime (666502619) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 333251324 + 333251325.

It is an arithmetic number, because the mean of its divisors is an integer number (333251325).

Almost surely, 2^666502649 is an apocalyptic number.

It is an amenable number.

666502649 is a deficient number, since it is larger than the sum of its proper divisors (1).

666502649 is an equidigital number, since it uses as much as digits as its factorization.

666502649 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 466560, while the sum is 44.

The square root of 666502649 is about 25816.7125908780. The cubic root of 666502649 is about 873.5088175455.

The spelling of 666502649 in words is "six hundred sixty-six million, five hundred two thousand, six hundred forty-nine".