66440401 has 2 divisors, whose sum is σ = 66440402. Its totient is φ = 66440400.

The previous prime is 66440393. The next prime is 66440447. The reversal of 66440401 is 10404466.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 66438801 + 1600 = 8151^2 + 40^2 .

It is a cyclic number.

It is not a de Polignac number, because 66440401 - 2³ = 66440393 is a prime.

It is equal to p_3920722 and since 66440401 and 3920722 have the same sum of digits, it is a Honaker prime.

It is not a weakly prime, because it can be changed into another prime (66440201) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 33220200 + 33220201.

It is an arithmetic number, because the mean of its divisors is an integer number (33220201).

Almost surely, 2^66440401 is an apocalyptic number.

It is an amenable number.

66440401 is a deficient number, since it is larger than the sum of its proper divisors (1).

66440401 is an equidigital number, since it uses as much as digits as its factorization.

66440401 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 2304, while the sum is 25.

The square root of 66440401 is about 8151.0981468757. The cubic root of 66440401 is about 405.0208819188.

Adding to 66440401 its reverse (10404466), we get a palindrome (76844867).

The spelling of 66440401 in words is "sixty-six million, four hundred forty thousand, four hundred one".