66808919 has 2 divisors, whose sum is σ = 66808920. Its totient is φ = 66808918.

The previous prime is 66808913. The next prime is 66808927. The reversal of 66808919 is 91980866.

It is a weak prime.

It is a cyclic number.

It is not a de Polignac number, because 66808919 - 2²⁴ = 50031703 is a prime.

It is a super-2 number, since 2×66808919² = 8926863315897122, which contains 22 as substring.

It is a Sophie Germain prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (66808913) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 33404459 + 33404460.

It is an arithmetic number, because the mean of its divisors is an integer number (33404460).

Almost surely, 2^66808919 is an apocalyptic number.

66808919 is a deficient number, since it is larger than the sum of its proper divisors (1).

66808919 is an equidigital number, since it uses as much as digits as its factorization.

66808919 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 186624, while the sum is 47.

The square root of 66808919 is about 8173.6723080877. The cubic root of 66808919 is about 405.7683306266.

The spelling of 66808919 in words is "sixty-six million, eight hundred eight thousand, nine hundred nineteen".