66256609 has 4 divisors (see below), whose sum is σ = 66289860. Its totient is φ = 66223360.

The previous prime is 66256607. The next prime is 66256621. The reversal of 66256609 is 90665266.

It is a semiprime because it is the product of two primes.

It can be written as a sum of positive squares in 2 ways, for example, as 25654225 + 40602384 = 5065^2 + 6372^2 .

It is a cyclic number.

It is not a de Polignac number, because 66256609 - 2¹ = 66256607 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (66256607) 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, 13432 + ... + 17689.

It is an arithmetic number, because the mean of its divisors is an integer number (16572465).

Almost surely, 2^66256609 is an apocalyptic number.

It is an amenable number.

66256609 is a deficient number, since it is larger than the sum of its proper divisors (33251).

66256609 is a wasteful number, since it uses less digits than its factorization.

66256609 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 33250.

The product of its (nonzero) digits is 116640, while the sum is 40.

The square root of 66256609 is about 8139.8162755679. The cubic root of 66256609 is about 404.6470714939.

The spelling of 66256609 in words is "sixty-six million, two hundred fifty-six thousand, six hundred nine".