66808813 has 8 divisors (see below), whose sum is σ = 71963136. Its totient is φ = 61842000.

The previous prime is 66808783. The next prime is 66808831. The reversal of 66808813 is 31880866.

It is a sphenic number, since it is the product of 3 distinct primes.

It is a cyclic number.

It is not a de Polignac number, because 66808813 - 2²⁵ = 33254381 is a prime.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (66808843) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 46138 + ... + 47563.

It is an arithmetic number, because the mean of its divisors is an integer number (8995392).

Almost surely, 2^66808813 is an apocalyptic number.

It is an amenable number.

66808813 is a deficient number, since it is larger than the sum of its proper divisors (5154323).

66808813 is a wasteful number, since it uses less digits than its factorization.

66808813 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 93755.

The product of its (nonzero) digits is 55296, while the sum is 40.

The square root of 66808813 is about 8173.6658238516. The cubic root of 66808813 is about 405.7681160272.

The spelling of 66808813 in words is "sixty-six million, eight hundred eight thousand, eight hundred thirteen".