66645871 has 2 divisors, whose sum is σ = 66645872. Its totient is φ = 66645870.

The previous prime is 66645851. The next prime is 66645889. The reversal of 66645871 is 17854666.

It is a happy number.

It is a strong prime.

It is a cyclic number.

It is not a de Polignac number, because 66645871 - 2²⁵ = 33091439 is a prime.

It is a super-3 number, since 3×66645871³ (a number of 24 digits) contains 333 as substring.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (66645811) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 33322935 + 33322936.

It is an arithmetic number, because the mean of its divisors is an integer number (33322936).

Almost surely, 2^66645871 is an apocalyptic number.

66645871 is a deficient number, since it is larger than the sum of its proper divisors (1).

66645871 is an equidigital number, since it uses as much as digits as its factorization.

66645871 is an evil number, because the sum of its binary digits is even.

The product of its digits is 241920, while the sum is 43.

The square root of 66645871 is about 8163.6922406470. The cubic root of 66645871 is about 405.4379675052.

The spelling of 66645871 in words is "sixty-six million, six hundred forty-five thousand, eight hundred seventy-one".