66808513 has 4 divisors (see below), whose sum is σ = 66834900. Its totient is φ = 66782128.

The previous prime is 66808501. The next prime is 66808519. The reversal of 66808513 is 31580866.

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 760384 + 66048129 = 872^2 + 8127^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-66808513 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (66808519) 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, 8938 + ... + 14611.

It is an arithmetic number, because the mean of its divisors is an integer number (16708725).

Almost surely, 2^66808513 is an apocalyptic number.

It is an amenable number.

66808513 is a deficient number, since it is larger than the sum of its proper divisors (26387).

66808513 is a wasteful number, since it uses less digits than its factorization.

66808513 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 26386.

The product of its (nonzero) digits is 34560, while the sum is 37.

The square root of 66808513 is about 8173.6474722121. The cubic root of 66808513 is about 405.7675086691.

The spelling of 66808513 in words is "sixty-six million, eight hundred eight thousand, five hundred thirteen".