66656309 has 4 divisors (see below), whose sum is σ = 66767820. Its totient is φ = 66544800.

The previous prime is 66656299. The next prime is 66656353. The reversal of 66656309 is 90365666.

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 53333809 + 13322500 = 7303^2 + 3650^2 .

It is a cyclic number.

It is not a de Polignac number, because 66656309 - 2²⁰ = 65607733 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (66656209) 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, 54854 + ... + 56055.

It is an arithmetic number, because the mean of its divisors is an integer number (16691955).

Almost surely, 2^66656309 is an apocalyptic number.

It is an amenable number.

66656309 is a deficient number, since it is larger than the sum of its proper divisors (111511).

66656309 is a wasteful number, since it uses less digits than its factorization.

66656309 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 111510.

The product of its (nonzero) digits is 174960, while the sum is 41.

The square root of 66656309 is about 8164.3315096828. The cubic root of 66656309 is about 405.4591328103.

The spelling of 66656309 in words is "sixty-six million, six hundred fifty-six thousand, three hundred nine".