66810649 has 2 divisors, whose sum is σ = 66810650. Its totient is φ = 66810648.

The previous prime is 66810599. The next prime is 66810659. The reversal of 66810649 is 94601866.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 61779600 + 5031049 = 7860^2 + 2243^2 .

It is a cyclic number.

It is not a de Polignac number, because 66810649 - 2¹¹ = 66808601 is a prime.

It is a Chen prime.

It is not a weakly prime, because it can be changed into another prime (66810659) 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, 33405324 + 33405325.

It is an arithmetic number, because the mean of its divisors is an integer number (33405325).

Almost surely, 2^66810649 is an apocalyptic number.

It is an amenable number.

66810649 is a deficient number, since it is larger than the sum of its proper divisors (1).

66810649 is an equidigital number, since it uses as much as digits as its factorization.

66810649 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 62208, while the sum is 40.

The square root of 66810649 is about 8173.7781349875. The cubic root of 66810649 is about 405.7718330191.

The spelling of 66810649 in words is "sixty-six million, eight hundred ten thousand, six hundred forty-nine".