66440393 has 2 divisors, whose sum is σ = 66440394. Its totient is φ = 66440392.

The previous prime is 66440383. The next prime is 66440401. The reversal of 66440393 is 39304466.

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., 56505289 + 9935104 = 7517^2 + 3152^2 .

It is a cyclic number.

It is not a de Polignac number, because 66440393 - 2⁸ = 66440137 is a prime.

It is not a weakly prime, because it can be changed into another prime (66440303) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 33220196 + 33220197.

It is an arithmetic number, because the mean of its divisors is an integer number (33220197).

Almost surely, 2^66440393 is an apocalyptic number.

It is an amenable number.

66440393 is a deficient number, since it is larger than the sum of its proper divisors (1).

66440393 is an equidigital number, since it uses as much as digits as its factorization.

66440393 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 46656, while the sum is 35.

The square root of 66440393 is about 8151.0976561442. The cubic root of 66440393 is about 405.0208656628.

The spelling of 66440393 in words is "sixty-six million, four hundred forty thousand, three hundred ninety-three".