66405265 has 4 divisors (see below), whose sum is σ = 79686324. Its totient is φ = 53124208.

The previous prime is 66405263. The next prime is 66405293. The reversal of 66405265 is 56250466.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 56250466 = 2 ⋅28125233.

It can be written as a sum of positive squares in 2 ways, for example, as 51667344 + 14737921 = 7188^2 + 3839^2 .

It is a cyclic number.

It is not a de Polignac number, because 66405265 - 2¹ = 66405263 is a prime.

It is a Duffinian number.

It is a self number, because there is not a number n which added to its sum of digits gives 66405265.

It is not an unprimeable number, because it can be changed into a prime (66405263) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 6640522 + ... + 6640531.

It is an arithmetic number, because the mean of its divisors is an integer number (19921581).

Almost surely, 2^66405265 is an apocalyptic number.

It is an amenable number.

66405265 is a deficient number, since it is larger than the sum of its proper divisors (13281059).

66405265 is a wasteful number, since it uses less digits than its factorization.

66405265 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 13281058.

The product of its (nonzero) digits is 43200, while the sum is 34.

The square root of 66405265 is about 8148.9425694381. The cubic root of 66405265 is about 404.9494729426.

The spelling of 66405265 in words is "sixty-six million, four hundred five thousand, two hundred sixty-five".